You can buy insurance policies to protect your business against the latter. (Although with Covid a lot of insurers are refusing to pay out, and some are being taken to court.)

Where there's no insurance it's reasonable for government to act as an informal insurer of last resort, because it's hugely more expensive and damaging to allow businesses that are otherwise viable to go to the wall.

You don't just lose a viable business, but you create losses that ripple through the entire system causing upstream insolvencies. So you lose the productivity of all the businesses affected and the spending power of their employees. It takes a good long time to rebuild both.

The problem is in the grey area where it's hard to tell if businesses are genuinely viable and just need temporary reinforcement, or whether they're already zombies and need to be killed off.

Patronage and politics makes this even more complicated.

But the principle is still sound: in a national disaster insolvency is not a clear signal of failure, and allowing all business to crash regardless will do much more harm than good.