The 2.5K Moneydrop and Stealth Money are generally the most risky methods there are. That's why I put another idea into practice with a friend who was only recently unbanned in GTA Online.
So I and a friend of mine did an action today that may work without being banned. We did the following:
My buddy filled his garage with free cars, which are cars that cost $ 0. Of course, you can also use any other vehicle that you can buy in the GTA Online Internet, but if you prefer not to invest money, you can also take free cars. He then had these delivered by the mechanic at LS Customs and I just had to get in and activate "Maximum Upgrade". So my friend had a car that was worth an average of $ 115,000 and could be sold directly to LS Customs. Cars stolen from the street can only be sold every ~ 45-60 minutes. There was a slightly larger limit on the number of self-bought cars, making it possible to generate more than two million dollars.
And if any of you intend to do this, I can only say that it is unfortunately not possible to cheat cars and drive them into the garage. The best thing to do is to sell them directly. We noticed that all the cars that I upgraded with Maverick unfortunately reset themselves after a while or are reset when you return to GTA Online. Of course, only the upgrade of the cars was affected. The cars themselves remained in the garage, of course.
If you upgrade a car with the cheat, you must not be in the workshop or in the car while the upgraded car is sold. Should you still be there, the seller will not get the money, but you, and that would of course not be nice. So if you upgrade with cheat, please stay outside of this transaction.
I don't know if this method is safe, so I cannot accept liability for this method. Money is always difficult.