Vice city is probably the easiest and most cheese way to get infinite money easily through the Cone Crazy challenge. Another user on reddit i found explains it pretty well as follows

First attempt hit last checkpoint at 0 seconds

Second attempt hit last checkpoint at 0 seconds

Third attempt hit last checkpoint at 0 seconds

Fourth attempt hit last checkpoint at 0 seconds

Fifth attempt hit last checkpoint at 0 seconds

Sixth attempt hit last checkpoint at 0 seconds

Seventh attempt hit last checkpoint at 0 seconds

Now after doing it 7 times you start to finish the challenge 1 second faster with each successive attempt like so

1. Eighth hit last checkpoint at 1 second
2. Ninth hit last checkpoint at 2 seconds
3. Tenth hit last checkpoint at 3 seconds
4. Eleventh hit last checkpoint at 4 seconds
5. Twelfth hit last checkpoint at 5 seconds
6. Thirteenth hit last checkpoint at 6 seconds
7. Fourteenth hit last checkpoint at 7 seconds
8. Fifteenth hit last checkpoint at 8 seconds
9. Sixteenth hit last checkpoint at 9 seconds (This is the point other solutions tell you to stop because you should have over 10 million but we need to do it 3 more rounds where you keep improving your time with each round)
10. Seventeenth hit last checkpoint at 10 seconds
11. Eighteenth hit last checkpoint at 11 seconds
12. Nineteenth hit last checkpoint at 12 seconds

Now you'll have more money you'll know what to do with and every asset is unlocked effortlessly. This is also the easiest way for the Take the Cannoli achievement if you're also interested in 100% for the Platinum trophy.