The promise of payment is the consideration. A contract is literally an exchange of promises. When you go into a car dealership and buy a car, they are exchanging a promise (you get a car!) for your promise to pay them.

The refusal to pay is a failure to live up to the promise - that is what makes it a breach of contract. If not paying meant consideration didn’t exist, then nobody would be able to sue for breach of contract for non-payment. If breach meant the contract was invalid, you wouldn’t be able to enforce the contract.

The promise of payment itself is consideration. The refusal to honor that promise is the breach of the contract. The contract itself doesn't become invalid because one party breaches the contract. Again, such an interpretation would fully the entire purpose of contract law.