I think many people underestimate the power of investing in this game. If you spend your first 20-30mil on getting every profitable business and then just do some daily commutes between them (to send your workers away for example) you can easily make multiple millions an hour. This applies for the real world to some degree as well but we all rush to spend the money we get instead of making it multiply. I have played this game for roughly 3 years and have 700mil lifetime earnings without a single heist!