how bad can I possibly be??

The problem is not that the Onceler is morally bad, but that he is rationally responding to bad incentives which lead to bad outcomes: he is indeed “doing what comes naturally” in the current (lax) regulatory environment.

If the only way to avoid bad outcomes is for everyone in your society to be morally virtuous and to have access to perfect information then you have a problem!

A better way would be to pay attention to outcomes and have a system of checks and balances that provides a feedback loop to correct the incentives that led to them, combined with an enforcement mechanism to punish violators.