It's easier to get a job when you have a job because of the mentality of hiring managers

They look at you like something is wrong with you if you're not working for a period of time

My only suggestion here is get another job before quitting until you're in the PhD program

Nothing to add, except that I agree with the below advice. Even though you have a decent safety net the below advice are all valid points. I don’t agree about the phd being a waste necessarily though. Really depends on your goals. In my field a masters is sufficient and there’s no pay increase if you have a phd. However, if I wanted to go into research a phd would be necessary and worth the expense.