2
no one will buy if servers are slow. no money for servers because of lack of sales. my guess would be bankruptcy within a year.
even though your income would be sellers, your customer is really the buyers. It's like a mall, you would be responsibile for upkeep to make the place attractive to buyers. no buyers = no stores. no stores = no upkeep. no upkeep = no buyers.
Basically, you have to charge rent.
not to mention your competition.