We all have read some comments in the subreddit about it's quite hard making money in the game, properties are not very profitable, and the missions that affect the stock market seem to be too few and too early.
I think I might have found why. When you open the store section in the pause menu, it says there is nothing available yet, but the console requests
this file.
It's a plain XML file where you will see that besides of the downlodable content from the special editions, there are 4 so-called "cash cards", ranging from $100,000 to $1,250,000.
Mirror of the file in case it goes down or changes
Images of the cards referenced in the file (converted from DDS format)
I may be wrong and I sincerely hope I am, but to me this looks like the explanation of why it's so hard to make money in the game: at some point (when GTAO starts?) you're supposed to buy game money with real money :(
This seems very un-Rockstar-y to me, so I want to believe there are other plausible explanations:
It's just a test, since it was not supposed to be public. Maybe something used internally?
They are redeemable items, not something you buy with real money. Maybe the prizes of some Social Club sweepstakes?
tl;dr: making money is hard because you're supposed to buy game money with real money at some point