Superbugs are true for the same reason reason covid is benign - nature selects for that which is best suited to it's environment

When the environment is one where antibacterials are everywhere, resistance is required. Resistance is selected for, and what competes out the alternatives is unstoppable. Being deadly is a fine reproductive strategy when there's an endless supply of sick just meters away and you can't be stopped.

Hospitals are an unusual environment. We should have decentralized them ages ago, but competition is literally not allowed so instead of having several smaller facilities we have consolidated state mandated monopolies. You can thank socialism for that too by the way.