I think that's the 6 '9's problem. If you have something with 99% uptime, how much more are you willing to pay for 99.9% uptime, then 99.99% uptime. It's risk vs cost. Many places in the US do the same thing with things like say snow removal. Instead of having expensive systems ready to go for the 1-2 days of year of snow, you just shut things down for a day and slow down a little.
That doesn't work for all systems, and not for all businesses, but I would say the mass majority can 'suffer' 24 hours without email or an LLM without everything going up in flames.
It's not only a 9's thing. If you can set yourself up to easily switch between providers, you also put yourself in a better bargaining position.
That's not always easy to do, but with something like inference providers it is, so why not kill two birds with one stone?