Is it true that, the SIA prize has to be relatively low to get wider adoption and make it a success?If the prize of SIA goes high, then it becomes expensive to store and people will revert o traditional centralised storage which are cheaper.
No, hosts decide their own pricing in Siacoin for storing data, and they adjust it to dollar prices. So the market value of the coin does not affect the pricing of the storage: If the coin goes up, hosts reduce the pricing, as they are competing with storage services as Amazon or Azure (that ask for a pricing in dollars)