Sia is pretty much a decentralized dropbox. It works like this, you as a user have data you want to store. Other users of Sia have storage available, they are your hosts. You engage contracts with other users that host your data and pay them in Siacoins.
If you want to host other peoples data, at this point you have to own 50000 (which translates to about €30 or $33 at the time of writing) Siacoins for you to start hosting. You as a host determine your own rates of Siacoin. The price of bandwith, price per TB per month, collateral per TB per month and the maximum duration of the contract is up to the user. However if you are expensive of course you will have less contracts assigned to you. Your transferred data is always encrypted.
My main question is why anyone would go through the trouble of signing up for an exchange, transfer their FIAT money to that exchange, buy Siacoin, transfer it to their wallet and start Sia to buy hosting? Dropbox and alternatives let you do that all within a few clicks. Don't get me wrong I really really like the idea and would use it too, but at this moment there seems to be a bit of a gap between me pressing the download button and actually starting to use the programme.
Since it is all nicely decentralized your files would be distributed on several locations at the same time. But what if you sign a nice cheap contract with a certain host and he decides to quit and never turn on his equipment? Your data will be fine, you can get it from others. But your contract is still there, will another host pick up the cheap contract? A smart contract will run on the blockchain that only pays a host when they keep your file for the entire duration, so that means the host is less likely to just quit. But who then picks up the contract?
At this moment another problem is the starting of all this. The best hosts are geographically close to you but at this moment there aren't that many. So for this to work there would have to be a lot of hosts already running before users join. I for example have around 1.2TB of cloud storage in use on another platform and I am a heavy user, so at this point the network is not reliable enough for me to split all the data onto many hosts for reliability. I think Sia is a great idea, I really do. But I think adoption is still far away.
