As a math professor, I agree with this. I'd also say, if you choose to get a PhD, then commit fully to it. In particular don't spend a lot of time on side gigs

As a math professor, I agree with this. I'd also say, if you choose to get a PhD, then commit fully to it. In particular don't spend a lot of time on side gigs unless you must. There are more PhD recipients than there are research jobs available, so any entry-level job that requires a PhD is likely to require a strong PhD, with a full-throated recommendation from your advisor.