Why do you have your own coin and blockchain?
Sia uses a custom, proof-of-work blockchain designed specifically for fulfilling payments and file contracts.
There are a few important reasons for having our own cryptocurrency and our own blockchain:
The Sia community runs the show
It gives us control over our own destiny. Sia is an enterprise-grade storage network, and we can't run that on a technology that isn't within the control of the Sia community and core developers. If Bitcoin or Ethereum have network congestion, fork, or are subject to some new vulnerability, we don't want to be affected by that. We can run fast and lean by being able to patch any issues as soon as we find them.
We also aren't subject to the development roadmap of another team.
We're on the same page
It helps align incentives across our decentralized network. Miners get rewarded in Siacoins for securing the blockchain, hosts receive Siacoins for selling storage space, renters pay in Siacoins to buy storage space.
We can have a laser focus
It allows us to create smart contracts built specifically for file storage. The Sia blockchain serves only to serve as a ledger for Siacoin transactions and storage contracts. And a Siacoin can only do two things - transferred from one user to another, or put into a file storage contract on the network.
Sia launched to the public on June 6th, 2015. Ethereum wasn't live for almost another two months, and wasn't designed to do everything we designed the Sia blockchain to do.
Our own crypto and our own blockchain are required. We are not trying to build something that may work in 10 years - we have already built a working decentralized storage network that is secured by Proof of Work.