I work close to the engineering school at a big Uni and often meet MEng students, at times in the past I had them help me out with ML projects that but usually I end up talking to them on the bus or in the 6th floor kitchen. So it's a question I ponder.

I had one student who did all the coding for a successful project that we wrote a paper about. I've talked to others who feel like they are "over their head" but are working on teams with people who know how to do all the math. That might be OK because there is a lot more to successful ML projects than being an individual contributor: very few people know how to manage ML projects and if you learned something about that it could be highly valuable.

If you study for a PhD you will definitely learn the math, but you've got an entirely different problem that you could be out of the workforce between 5-10 years and the market could look entirely different then than it looks now.