Your criticism of GTA V's economy and money progression applies to every mainline GTA. Lets take a look at GTA San Andreas, you start out with barely any cash. You're a low level gangbanger with a family home and that's about it.
Right after the first mission or two, Los Santos is your oyster. If you find a fire truck you can make $80,000 for twenty minutes of easy work. You then could gamble your money on horse races or do more activities that rake in easy cash. Such as vigilante missions, you start one up and then run in a fast food joint. Boom, the target is killed.
So after an hour of work in San Andreas you could potentially have a few hundred thousand dollars or more. Without exploits, doing activities and then betting on horse races may take a bit longer, but its still easy money.
Without being an entrepreneur early in the game, you can wait until Las Venturas opens up. Bet on blackjack tables, raise your gambling skill so you can go to the million dollar table. Better yet, you don't actually need a million dollars to bet that amount, if you lose you go into debt.
Fortunately the Japanese Yakuza casino has a save point right at the entrance. So any time you lose, you can reload your last save and try becoming a millionaire instantly once again.
GTA Vice City has similar exploits and oddities. GTA has never been a series where money has to be earned earnestly with tons of effort, if you find a way to make money, and a lot of it, in a timely manner, more power to you.