use stock market you save game before buy one that you want then just go to sleep before come back to check and if you lose money reload your save and if you get money just sell it and use that money to repeat this process hope this help

Personally, I just use the slots in the casino. Kinda just spam them, and when you get double the amount you've earned, raise the amount by a 20th of that (if you have 100, go by 5s, wait until that goes to either 200, or 500, and then raise it to either 10, or 25, depending on how safe you wanna be, you get to the points limit very quickly. In less than like 10 minutes once you're at limit you can gain about 100K from it. The slots are extremely generous. Just remember to spam them like hell, to speed it up. Vinegara premium also works really well if you're trying to just stream it out, since you can keep it on fast, and let the money start rolling.