I worked for a small contracting company that did work for several larger (but not FAANG) companies for >10 years. I quit 1.5 years ago after being burned out for quite a while, and I'm enjoying life for now. The thought of going back to work is a little stressful, and I'm holding out for as long as possible :)

Reasons for my burn out:

- Unreasonable expectations from stakeholders. "We need x, y, and z done by Friday" with no regard for developer input on what that actually entails. Not all projects are like this, but some are. It's fine when it is rare, but the more frequent it is, the more burnout it causes.

- Frequently changing requirements, or total shifts in what needed to be built from one week to the next.

- Working on projects with outdated dependencies and never given any time to refactor to support updates (i.e. working on an Angular 4 project when Angular 12 is out).

- As a contractor, it always feels like you need to perform, or the company you're working for will drop you.

- As a contractor, the clients' internal FT devs have seniority and will make decisions that are not always in the best interest of the project.

- Abruptly being moved (without much input) from one project to another takes a toll, especially when you care about what you do.

- Not enough vacation time. For most of my 20's, I got two weeks a year. For most of my 30's, it was three weeks a year. That's not really enough time off to enjoy life.