Just robbed the sh*t out of the stores for a long time, did a lot of missions, got me 50k. Logged out for about 1h, came back, still the same money when I started it (10k).
The servers arent saving anything. Might as well play only for fun. Dont grind or you will be severely disapointed soon.
I haven't lost anything to the servers - just the missions. I've had missions where I've lost $15000, just from hospital bills (ironically, the funnest, most violent and intense missions - where people die a lot).
So even if they fix the bugs, there's still a fundamental problem with the design (easily fixed though).