They had all the incentives to make all those bad bets. And to counteract those incentives further regulations needed to be enacted.
What's good for the company in the long run is not necessarily what really happens because companies consist mostly of short sighted decision makers driven by short term incentives. They will happily collectively burn their respective markets to the ground if it brings them short term profit.
What helps large corporations to survive this is their sheer inertia. Banks are kind of special because they, despite being huge, can topple very quickly.
It’s truly absurd to argue that banks have no incentive to limit lending to make sure they get paid back. The 2008 crisis proves no such thing. Banks simply made a lot of bad bets.