This story brought back memories for me, some fresh and some distant. My IT career (in what feels like a past life) was a lot like what you described. On-call 24x7 with a 2 or 3 week rotation, and supporting more and more systems with the same level of staff. It never got as bad as you had it but definitely became a grind.

I left when a new role that I had negotiated fell through. The thing is, I had always been drawn to the markets and really wanted to be a trader, so I spent a good 5 years or more going down that path. I actually figured out fairly quickly that I didn't want to sit at a computer and trade so I made use of my IT and programming skills to develop a trading algo. But, it never got good enough to let loose. Then:

It took an epiphany to make me realise what path I was going down. I had been prepared for it all my life. I even wanted it, but deep down, I wasn't cut out for it.

I was putting all of my creative energy into something that I don't believe in. I had mistakenly convinced myself that I needed money in order to create but I had it backwards. Money can be a tool but we are creators first and foremost.

I'm glad that you got out.