Ask HN: Freelancing while going back to school?

Over the last 18 months, I've been taking university courses in mathematics and physics for the first time (I'm a self-taught engineer), and I've found myself wanting more and more to commit fully to study. I daydream quite a bit about pursuing a masters in mathematics, focused on statistics/ML-relevant math, while freelancing 10-20 hours a week to cover my cost of living.

I'm a software engineer with enough years of experience to qualify for a freelancing service like Moonlight, and I have a good enough network to find contracts on my own if need be.

I was hoping someone in the HN community could share their experiences with a similar life move. Have you ever taken time off from your career to go back for a Masters, and if so, was freelancing a viable option, or was the workload too great? Did you find it set you back in your career in anyway?