I would not quit the program until you have obtained a job offer and been granted another visa classification, such as an O-1, cap-exempt H-1B, or cap-subject H

I would not quit the program until you have obtained a job offer and been granted another visa classification, such as an O-1, cap-exempt H-1B, or cap-subject H-1B. You need to check with your international student office but I believe that if you just quit the program, you will be out of status without any grace period. And that's correct about your master's degree OPT - it's gone.