I've experienced this professionally. It's super debilitating. At some point, the only thing that you are willing to spend energy on is preventing the last fire you're exhausted from just fighting from happening again. I don't know what I'd have done if I didn't have good support from my manager at the time. He cleared a lot of expectations of other deliverables out of the way, so I could stabilize the infrastructure. Now, I know enough to work the politics to give myself room to do this work, but junior me couldn't have done it alone without cracking.