Most companies don't know how much downtime costs them and from their behaviour seem to treat it either as $0/hr or $infinite/hr. To be fair, it's difficult to estimate correctly. Apart from the direct loss of income there is also reputation loss, possibly reduced signups and increased churn, etc. It's not at all constant either, one outage per 10 years will give you a radically different reputation than one outage per week.

It's also working out which outages matter the most. A 10 day outage is not equivalent to 10 1 day outages, the latter has a multitude of important reputational risks - but the former is quite possibly enough to end the business completely.

Depends on how you value the potential outcomes. A while ago, I think it was Gitlab that didn't check their backups and they were a dud.

That caused quite a few problems...How much is it worth to them after the fact? I'd say a fair bit.

But hindsight...

If you run a fairly discretionary web app, like perhaps a game where downtime will cost you lost revenue for the time period but that's it, it's probably not worth it.

If you are running a communications platform like Slack or Gmail, it's hella worth it.