It's a glitch and it seems like someone already made a video about it-
!This what you do(incase if the video has been taking down)
Step 1- Buy the motorcycle 80RR(the one that costs $15,000)
! 2- Upgrade it as much as you can so the sell price will be high
! 3- Enter the bike and go to any mod shop, when you enter the mod shop and ready to upgrade then press start> go to the store and when it loads back out from it. You should be standing inside the mod shop while your bike is outside, go out and enter your bike and take it back inside again and press start> go to store > back out again then you should be outside the mod shop on your bike…
! 4- If you've completed step 3 then all you have to do is- enter mod shop with your bike and sell it, when it says sold press start immediately and go to store> then back out and you will reappear outside again… Just keep doing this and reselling your bike, the more upgrade you make on your bike the more money you get. make sure your doing this in , when on GTA 5, press start go to **<play gta="" online=""></play>**then …. Hurry up, it will get patched soon when Rockstar makes the upgrade for the free money...
Thx for this bud i made 90k in a hour. Only because im a low level and cant buy upgrades to the bike therefore i could only sell it for 1.5kmax at a time.