I have vaguely understood that they rely on their own blockchain with their own cryptocurrency.
But why are they not relying on preexisting blockchains like ethereum which are designed to be multipurpose ?
What are their exact working principle ? Indeed up to now I was under the impression that storing data on a blockchain is very costly.
Edit: I have also read this answer, which brings a lot of good elements of understanding, but I am still missing something in terms of seeing what Sia and Storj bring that IPFS or SWARM did not already have.