分享我嘅Bitcoin掘礦記錄。注意，我不推廣掘礦。Sharing of my Bitcoin Mining Journal. I do NOT promote Bitcoin Mining. (English in the middle)
Bitcoin升值，市場對掘礦嘅意欲都大增。8月當Bitcoin升破$3000之後，我就開始參加掘礦呢個活動，並且每日都作記錄同分析。今日我終於決定詳細分享我嘅掘擴手記。雖然發生左嘅事係冇可能再一次完整地經歷，但我相信Bitcoin嘅故事唔會完結，隨著時間嘅流逝，總結出嘅結論都可以重新應用，呢個亦都係以前Economics堂嘅其中一個主要目的。就等我獻醜為大家分析一下。
所謂掘礦，其實就係參與Bitcoin網絡交易及計算網絡嘅一個統稱，而掘出黎嘅礦叫做Block Rewards，意指參與計算後所得出嘅獎勵，即係Bitcoin。當中有好多複雜嘅原素，我初時亦都唔明白，所以呢段期間不停咁學習同觀察，希望可以總結出當中嘅規律。
首先掘礦係需要有部礦機。原本掘礦最初係普通電腦就可以，而家就要用到專門硬件，因為掘到嘅礦Bitcoin價值慢慢提高，有人就專門做左特別嘅硬件出黎，而呢啲硬件比普通電腦貴，亦都經常賣斷市。我就因為環境嘅關係，選擇左用雲掘礦。雲掘礦比自己有部機去掘礦簡單得多，而我只係對掘出黎嘅Bitcoin同當中嘅運作有興趣，所以我都冇諗太多就買左掘礦合約。
當然選擇要好小心，市面上9成9嘅雲掘礦服務都係輸打贏要，甚至乎隨時更改合約令自己收益大減，所以我都好小心咁揀。由於我本身嘅績蓄唔多，揀啱左就All in。今日睇番當日嘅決定係蠢左，因為如果我一開始係直接買Bitcoin而唔係買盒約，而家已經直接升值接近一倍。另外由於已經All in左落去，今日知道直接買Bitcoin好啲都冇能力再買。只可以話係交左學費。
掘礦要知嘅事好簡單，就係 成本 同 收益。成本係礦機 或者 雲掘礦合約價錢，再加每日嘅電費或管理費。淨收益就係每日會收到幾多Bitcoin。初時我嘅預計係淨收益會隨住Bitcoin價格上升而增加，因為我嘅合約係寫明管理費每日係計美金，但掘出黎嘅係Bitcoin；管理費係以掘出嘅Bitcoin黎扣除，Bitcoin價錢越高，所扣除嘅Bitcoin越少，即：
作為成本每日扣除嘅Bitcoin數量= 管理費 美金 / Bitcoin 價錢
由於當時所選定嘅公司嘅合約隨著Bitcoin價錢爆升而不停加價，我只係好粗略咁計就買左呢啲雲掘礦合約。當初計算嘅結果係300日左右以美金計算係必定會回本，而我買嘅合約係冇有效日期，只要每日所掘出黎嘅Bitcoin數量係多過作為成本每日需要扣除嘅Bitcoin數量，佢就會永久咁運行。當時覺得300日回本期之後嘅就係純利，間公司亦都信得過，呢個投資對當時嘅我黎講係非常吸引。
我嘅計算方法係咁：
一年回報 = [(每日掘出數量 - 成本嘅Bitcoin數量) x 365] x 第一日嘅Bitcoin美金價錢
我係分左幾日去買入。100%完成買入雲掘礦合約之後，我已經唔再心急去買入合約。慢慢開始再學多啲Bitcoin嘅知識。然後留意到掘礦難度呢個概念嘅重要性。
要了解掘礦難度，就要從掘礦獎勵黎講起。一部礦機加入Bitcoin網絡，除左係連線之外，其實係需要參與計算，並且係全世界所有礦機互相爭奪，最先計出複雜嘅加密問題先可以得到獎勵，所以Bitcoin先會被分類為加密幣，而非之前的數字幣。Bitcoin從出現開始就有一條規舉，當加入計算嘅礦機計算能力(Hashrates)增加，難度就會提升。增加幾多，難度就響一段時間之後按比例提升幾多。
問題開始出現。原來掘礦嘅成本收益係唔可以用linear嘅方法去計。就如同一般嘅機會成本計算一樣，原來係Earlier is preferred to later.
早啲掘係會比遲啲掘得到多啲Bitcoin，遲啲掘就會多啲人掘，所以難度高啲，掘得少啲。我原本個計算係300日可以回本，但因為個淨收益其實係隨時間下跌，變成左要由頭再計過，而且係要用Excel去預估。
睇番先前嘅紀錄，每一次難度轉變一般係12至13日。我嘅假設係每個時期平均嘅難度提高約7%，簡單黎講可以掘到嘅Bitcoin就會減少7%，我實際收入亦都減少7%以上。我嘅計算方法係重覆100次下面嘅formula：
淨收益 = [上一期掘出Bitcoin數量 x ( 1 - 難度上升百份比 )] - (管理費/Bitcoin價錢)
價錢不變，第34星期已經出產唔夠扣減管理費，真係嚇左一嚇。
當然，我知道呢個價錢不變嘅計法係唔恰當。價錢一定會變，如果我預價錢唔變，即係冇利潤，都唔需要買。所以我用左好唔科學嘅方法去估計價錢係幾多。最後得出要2年以上先回到本嘅預估。
其實回本呢個概念係有兩方面。一般嘅投資黎講係計番錢，即現金、美金。只要不停估Bitcoin會上升，咁總有一日Bitcoin 計算番美金係會等如我投入嘅金額。
經過左一段時間之後，我再發現出現左問題。因為太多人好似我自己咁加入掘礦行列，而且唔再係散戶，多左好多計算能力投入去掘礦。我開始要將計算嘅預估再改變。
原本係單估計價錢，再變成要估計埋難度嘅上升。即係我預估嘅試算表要每一個時期都要入兩個我估計嘅數值入去。呢個計算嘅複雜程度大大提升，而且亦都開始唔會準確。
做晒所有計算，我得出嘅結論係唔好掘礦。睇好Bitcoin就直接買入Bitcoin。我用番當日所投入嘅現錢及當日嘅Bitcoin價錢，計算當日可以買到嘅Bitcoin數目，再用番今日嘅價錢黎計，如果係直接買入，已經係穩賺70%以上，相信世界上都冇任何投資工具可以有呢個回報。更加重要嘅就係唔需要再冒不必要嘅風險...
但我呢個故事真係會響呢一度完結？當然唔係啦。事情冇咁簡單，但之後要寫嘅野太長，我會留番下一篇文再講。
This time, I would like to share my Bitcoin mining journal. Please note, I do not promote Bitcoin mining.
Bitcoin mining is hot since the price shot above US$3000 in August. I joined as well, and I analyzed my progress from time to time. I would like to (re)start my Bitcoin journal today because I have more followers and higher visibility now. Although these experiences will not replay entirely, I believe the learning will apply to Bitcoin in the future once again, like what Economics teacher told their students.
Bitcoin mining is a term that describes the participation in Bitcoin network and processing the transactions. The mined output is called Block Rewards, yes, these are your Bitcoin. There are a lot of complex variables in mining that I do not understand them entirely at the very beginning. That is why I look closely on the topic and hope that I can generalize them one by one.
To join mining, you need a miner. It is now a specially designed hardware that is more expensive than a high-end computer, with special chips called ASIC. I choose not to buy a miner (well, it is hard to get anyway) and joined cloud mining. Cloud mining is simple, and help me to just get the mining done, saving time for me to understand more about the ecosystems.
Of course, most cloud mining services are scam. They are not regulated and can change your service terms as they wish to. I did not have much spare money for investing, so I just spent all my money into 1 mining service I have chosen. In fact, I realize now this is not wise, because I should buy Bitcoin instead of buying mining contract. It is too late, anyway.
After all, everyone is looking for how much they earn, the net income. This means you have to understand the structure of the cost and income involved. Cost is either a miner, or a cloud mining contract, and electricity costs or cloud mining maintenance fee. I am fine with the arrangement of cloud mining because the maintenance was deducted in a fixed sum in US dollar, from the mined Bitcoin. The formula is:
Costs in Bitcoin = Fixed US$ Maintenance / Bitcoin Price
I do not think too much before I buy the contract because the contract cost was raising rapidly and I believed I would break even within 300 days, in US dollar terms. The fixed maintenance cost in US dollar would be deducted from the mined Bitcoin outputs. When Bitcoin price increases, the number of Bitcoin deducted for costs is lower and I can get more net income in terms of Bitcoin. Very attractive, right?
The formula I use was:
Annual return = [(Daily mined – Maintenance) x 365] x Bitcoin Price at the day of purchase
I only realized the importance of Mining Difficulties after I spent all my fund. In brief, it can be treated as a factor that made my Bitcoin net income decreases over time. As Bitcoin draw more attentions, the participants could increase and therefore the processing power of the whole network could increase, making the competition intensifies. The Bitcoin network would therefore increase the mining difficulties to balance the network, and decrease the average return for each participant. The difficulties should increase the same percentage as the processing power (Hashrates) increase, and the return would also decrease in the same percentage of this increase.
That is, as time goes by, the net income decreases. I had to recalculate with Excel this time.
What I did was studying the past record. The difficulties adjusted on average 12 to 13 days, with average of 7% a period. My mining income before maintenance fee would also decreased by the 7%.
Net Income = [Previous Mined amount x (1 – difficulties adjustment percentage)] – (maintenance/Bitcoin Price)
With this calculation, holding the price unchanged could make a contract termination in 34 weeks. I was shocked.
Yes, I know. It can’t be. The price MUST change, and therefore I had to re-model my projection once again, with 2 variables assumption. This made the projection better as I could enter what I THINK it could be. And sometimes, I told myself Bitcoin price will increase to a point someday that make the mined Bitcoin x Price = my money spent.
With all the calculation, my current conclusion is to buy Bitcoin, not cloud mining contract. If I used the money I spent on cloud mining to buy Bitcoin, the net worth of my money would have doubled today. There is no investing instrument that can get this return within 2 months. Best of all, buying Bitcoin do not need to risks contract terminations.
My journal does not end here. I am writing the next part at the time you see this story. _
See also
Bitcoin 我的掘礦記事報告 二 / My Mining Journal - 2
Bitcoin 我的掘礦記事報告 三 / My Mining Journal - 3
Bitcoin 我的掘礦記事報告 四 / My Mining Journal - 4
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