OpenRent[1] founder here. I was the only technical person at our company until we hit 1m users (certainly only person who could restart/switch servers).

I guess the question is, what happens if the server goes down whilst you're at work? The answer is that if you're constantly fighting fires 9-6, your software is probably severely broken. I'd suggest this is pretty unusual, or at least, I've never heard of software being held together like that at a company that still exists.

You wouldn't want the servers to go down whilst you're at work, in a meeting, or out to dinner with friends. So you design things to be as redundant as reasonably possible.

Then when you make a mistake, you fix it so it never happens again.

Server fear should be the least of your worries. As a founder, lots of things can go wrong that will interrupt a holiday or downtime. In my experience, it's rarely, if ever, software or hardware issues.

[1] - https://www.openrent.co.uk