Unfortunately, there are no easy exploits to generate cash, but that doesn't mean you're out of luck. The flip side is that if you're eyeing a yacht in GTA 5 Online that costs eight million GTA$ you may look at your in-game bank account and laugh. The company behind the Grand Theft Auto series has done an impressive job of consistently plugging any holes in GTA 5 Online, making it a lot more difficult for players to get fast money without putting in work first.
If you hate glitches, bugs, exploits or other workarounds that let you skirt the rules of video games you should respect the hell out of Rockstar Games.