Studies will suffer even more if you're unsure of where your next meal is coming from.

I got my master's in software engineering half time while working full time as a software engineer. During those four years I was also volunteering once a week, had a few side projects going on, wrote a book that made >$50,000 over the last two years, did freelance work, and maintained a relationship (got married two days after I graduated!).

There were certainly periods of time where I didn't see friends much, and my husband had to (gasp) cook dinner once in a while, but it was doable, and I graduated with a 3.7 GPA. I'm not a genius, I certainly did my fair share of procrastination, it was mostly just about making almost every day a "work day" (at least for a few hours), keeping things interesting by alternating between different types of work, and finding creative times/ways to study (commuting, lunch break, doing class busywork watching TV in the evening, etc)

I don't think I would have gotten "more" out of the program by quitting my job and just doing that full time. If anything, the financial stress would have made things more difficult.

Tons of students do part time min wager jobs and do just fine. You learn stuff from working those jobs alone!