Most people you talk to on the street do not understand how "Internet Money" could possibly have value. We try to point at Proof-Of-Work as the explanation, but it's often too complicated and the mind rejects the idea. Too much information too soon. After many many attempts of explaining POW to people who know nothing about crypto, the following is how I've refined and simplified the idea.
https://passwordsgenerator.net/sha256-hash-generator/
This website shows us the hashes of the most recent blocks.
We can see here that it takes a whopping 18 leading zeros
on a Bitcoin block hash to win the lottery.
The chance of one leading zero is 1/16^1 = 1/16
The chance of two leading zeros is 1/16^2 = 1/256
The chance of 18 leading zeros is 1/16^18 = 1/4,722,366,482,869,645,213,696.
On average, it will take 4.7 sextillion hashes (21 zeros) to mine a single block.
(Assuming a difficulty of 18 leading zeros.)
To confirm that this number makes sense: We can see that the Bitcoin network is producing 48.61 Exahashes per second (18 zeros). The Bitcoin community changes the difficulty every 2 weeks and tries to peg the average block time to 10 minutes. 10 minutes is 600 seconds. 48.61 * 600 = 29,166, so the Bitcoin network is pumping out 29 sextillion hashes every 10 minutes. This means the difficulty is actually set a little bit higher than 18 zeros, but also less than 19. A difficulty of 19 leading zeros would assume 75 sextillion hashes every 10 minutes.
It's not hard to see why skeptics of Bitcoin say that it wastes energy. The amount of energy being used in the competitive Bitcoin hash lottery trumps the output of many small countries. However, this energy expenditure is a necessary evil because it is the foundation of what gives Bitcoin value in the first place. As renewable energy takes the place of pollution-based energy this argument will be all but squashed.
Unlike the Federal Reserve and other central banks, the Bitcoin community has a massive incentive to keep their promises and ensure that Bitcoin inflation acts the way the community has decided it should act (consensus). No one in the Bitcoin community will allow anyone else to generate Bitcoin unless they follow these rules of Proof-Of-Work. Doing so would devalue the currency and the entire community would lose money. Even worse, the community would lose reputation and Bitcoin would be devalued even further.
This is why Bitcoin is a more trustworthy currency than anything a central bank or government has to offer. A centralized authority can print money out of thin air whenever they deem it necessary and, in the process, devalue every other dollar in the ecosystem. This is how countries like Venezuela experience a death-spiral of inflation that bombs their entire economy: the government simply keeps printing more money and no one can stop them.
This is not the case with cryptocurrency. This is why crypto is so valuable: you don't have to trust a central authority to have your best interest in mind. These communities regulate themselves for the good of everyone in them.
This explanation of proof-of-work was still a little bit more complex than I wanted it to be. I made the math part optional because it can be a big turn-off to the average person. I feel like this ELI5 post starts well and starts to go down a rabbit hole at the end; such is crypto.
The thing I've had the best experience with is hammering home the lottery analogy. Everyone knows what a lottery is and it shows how Bitcoin can't just be, "Created out of thin air." In fact, if anything's created out of thin air, it's fiat.
Understanding POW
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Blockchain Competition is Projected
Cryptocurrency To NoCurrency
Ultimate Blockchains
Open Source Decentralized Cooperative Capitalism
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ASIC Mining Rigs
Quadrillion Dollar Market Cap
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Future of Decentralzation
The Real Bubble Is Not Crypto