Just save scum the slots. They aren't as rigged as actual slots either, afaik. So, you should have no issues getting enough coins that way. It might even be faster than grinding for money.
Unfortunately I've discovered the opposite to be true. Slots will absolutely bleed the player dry unless save states are used to cheat.
The slots are rigged just like real slot machines. By that I mean you can only win on any individual pull if the machine is in a "win" state, and the state of the machine is randomly determined between each pull before inserting coins. Likewise, you can only line up BARs or 7s if the machine is in "jackpot" state. The main difference it has from a real slot machine is that it does not track the house take, so its win states are based on pull-to-pull RNG instead of being calibrated to a percentage of coins inserted into the machine over a long time. There is also the "Lucky" slot machine which can be any one of the machines in the corner, and it gives slightly betters odds of going into a "win" state.
So in theory it is quite possible to have a big winning streak and beat the house edge over time.
Except for the fact that...
1 - The only way to tell which machine is the lucky one is by playing every machine a ton and recording statistics on your wins over the course of a few hours. The lucky slot machine is randomly determined every time you enter the game corner, so leaving the map means you have to start over.
2 - The lucky slot machine can be machines unavailable to the player (NPCs using it, out of order, belongings left behind). The lucky slot machine is also bugged to where it can be a non-existent machine off of the map.
3 - The slot machine reels are bugged to where 7s or BARs will not line-up properly despite the machine being in a "jackpot" state.
