Other folks have already pointed out how this is unenforceable, but I'll give a very tangible example.
Twitter (and Instagram) ToS prohibit selling handles and yet I've been on both sides of those transactions before. You just offer the person a "consulting" contract, part of which is delivering the handle
Why wouldn't the buyer just pay the seller and not bother with smoke and mirrors? It's not as if Twitter or Instagram know about the "consulting" contract.
Twitter (and Instagram) ToS prohibit selling handles and yet I've been on both sides of those transactions before. You just offer the person a "consulting" contract, part of which is delivering the handle