Basically the best method I believe is through buying and selling stocks. This guide will show you how to become a billionaire in less than 5 minutes (if you're quick).

Warning: it's for single player only!

1. Download C.E. (Cheat Engine) and run it
2. Run GTA 5 story mode and load as any character with some cash
2. Click: ''select a process to open'' in C.E.
3. Choose a GTA5.exe process
4. Go to phone and select 'internet'
5. Go to Money and services
6. Choose either: 'LCN' or 'BAWSAQ'
7. From there go to 'Markets'
8. Choose any of the profitable stocks (with green arrows under 'Avg. Change %' table)
9. Buy e.g. 5 stocks or more
10. In C.E. in the 'value' write the number of stocks you bought. In our example it's 5, so write 5.
11. Back in the game sell 1 stock
12. Go back to C. E.and write 4 instead of 5
13. Then click 'next scan' in C.E.

Now, depending on game, you could already end up with 1 'address' and 'value' in C.E.
If not, sell 1 or few more stocks until you have just 1 option available.

If you have just 1 address, then select it and click on the red arrow.
It moved the address to the bottom.
14. Double click on the value and change to e.g. 5000000

That's it. You have 5.000.000 bought stocks in the game.
15. Sell all stocks and make profit.
Just in case you can add a few more thousand stocks to yourself in C.E. before closing it

Note: * Don't close C.E. in case you want to change the number of stocks owned later in the game (but you'll have to find the 'address' and 'value' all over if you change the character).
** Make sure you close C.E.after it's all done.

If you have questions regarding this guide or just got something to say, leave me a comment below.

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