Because he is getting the ideas for free?
This is not true. He said he will put 2500USD on the table for the best idea. This is not "for free".Why don't people just post their ideas with some sort of disclaimer that the 2500USD have to be paid before the idea is adopted?
Many people just don't get the point that an escrow is absolutely useless. The OP could very well put the 2500USD to an escrow,
let you post your ideas and then ask the escrow for a refund because none of the submissions meet his definition of "a good idea".
The escrow is a misconception, does not give you any additional security, and is - in the way it is used here in the forum - completely pointless.
Why do people still do it?
You basically say escrow is useless because OP can say there were no good ideas and take his money back but you state the text in red? If OP is not truthful about putting the money on the table then he
is getting free ideas.
When I ask the OP to use escrow I would expect some sort of guarantee that there
will be a payout and maybe let the escrow person confirm this as well so he doesn't pull the "there were no good ideas" excuse. If OP does that then I assure you there will be pages upon pages of decent ideas. But this will never happen since no one (in their right mind) will pay $2500 for an idea so everyone is basically wasting their time.