In another comment you mentioned that you've already used your post completion opt.

Can you apply for a STEM extension now? That will keep you in the country and let you work for another 24 months. Try to get the highest paying job you can and then Aggressively save to pay off your student loan?

After that to continue staying in the country you'll have to get an H1-B. Having graduated from a US masters program you have slightly better chance in the MS cap but the odds may not be in your favour.

The safest option would be to plow through your PhD program. But you probably already knew that.

Quitting the program and getting a job might be a gamble, but weighing the risks is something you'll obviously have to figure out.