Hey there.
I don't see what's freaking you out here. In the rest of IT world when external developers are hired by a company they're paid at the delivery. I'm an IT engineer (not a coder, on the project management side, I can code but I'm really not good at it
) and that's just how the world works. That's why if you feel ready for this task we'll agree on a technical book of delivery of what should be the final product. As long as the final product fulfills the requirements the escrow must releases the funds to you.
It's exactly the same in the rest of the world: you make a contract with a dev team, they do the development and if the final product fulfill the requirements you have to pay them. Nothing wrong here. And if you're not able to draft a technical book of delivery precise enough to cover you, that means you shouldn't work on independant project from the start and just go work for a big company ^^
I can't just pay you and then hope you'll develop what I asked for, see my point?
And for the last: ICO developers are the LAST priority not the LEAST. I can't hire a development team if I don't have the idea, the target, the market study, the funds and the strategy for the ICO... That would be like hiring workers for a house before having the field and the loan from the bank xD
If you feel like you're able to do this and are interested, just tell me what guarantee you're looking for and I'll be happy to comply if I can!