As a relatively unremarkable data scientist/machine learning engineer of about 5 years, I've been keeping an eye on DS/ML positions as they tend to give a sense on what is important to companies in that space, although I'm not actively looking for a new role. More and more positions seem to require Ph.D. credentials even for non-senior roles, even though modern DS/ML tooling doesn't require it.
If I ever left my job I might have to quit DS/ML and do something else entirely.
Nah, you wouldn't have to quit. If you've got 5 years experience, even on non-cutting edge projects, the PhD won't matter. Sure, you won't be able to get any job you want, but there are lots of ML jobs that list a PhD requirement that will nevertheless jump at the chance to hire someone with practical experience.
That'll only be a problem if you're up against significant number of candidates that have both experience and a PhD. HR will certainly filter resumes based on something as clear-cut as a degree when they can. But they can't just filter everything out and tell the hiring manager he's SOL. So you don't have to check all the boxes as long as you check enough of them, and you're competitive with the other candidates.
At the same time, nobody is going to do all that well if they just apply online and cross their fingers. You need some kind of human contact, either though an introduction to an insider through your network, or through a recruiter of some kind. It takes a bit of time to develop the relationships, but it's quite doable and worth it, even for introverts. Best to start before you're interested in changing jobs.
If I ever left my job I might have to quit DS/ML and do something else entirely.