Are you talking about SP mode?
I kinda wonder if they didn't make it hard to get money in SP on purpose to convince you to try MP where it was more possible to get that expensive stuff (and they had MTs to encourage you to pay extra)...
(and this is why MTs are bad people. It does encourage stuff like that. And even if they didn't, that thought will be in my mind when playing SP that SP was gimped some to encourage me to play MP even when I'd prefer SP except some things were done better in MP. Including being able to actually do something other than the stock market to get enough money to get the expensive stuff. Also, with how they allow you to keep cars in MP vs. SP).
I think it's just bad balance because it's easy to have over 2 billion per character when you finish the game. But you have to exploit the assassination missions and stock market. It's easy to make hundreds of millions on the BAQSAQ too because it's easy to get anywhere between 10-100% returns over a few days or a week and just use multiple save files with different stocks. So if you exploit the stock market, you basically break money in the game.
And, if you don't do this, there's no other way to make millions. Heck, there's no other way to even make hundreds of thousands. You get good revenue from the properties once you buy them.. my Michael gets about $800,000 a week but you could never buy that $250ish million worth of real estate without abusing the stock market. Only other way to really get good money are suitcase drops, and they're not repeatable anymore. Altruist never was, and when they fixed the respawning underwater suitcase, it bugged out the weed farm. In-game it still to this date says we're supposed to be able to raid it every week (usually between $10k-100k spawns) but after Rockstar fixed the underwater suitcase, they broke the weed farm from respawning. And they never fixed it because they mostly just ignore GTAV to make GTAO content.
So basically either you never have enough money and no good way to make money... or you break the game and make money pointless by abusing the stock market. For a game that's supposed to be about making money via Heists, they were incredibly lazy about money balance. 5 years on a game and can't even get a QA guy to spend 1 day tweaking the money amounts to be even remotely balanced.
