The server really requires a economy re-balancing. The current ways of spending money are way too cheap and/or useless (or they limit you in other ways).
There are currently 5 ways of spending (or reducing) money:
1) Property
2) Transport
3) Weaponry
4) Useful/Useless items from stores etc.
5) Wealth Tax
1) Property
A player can own up to 5 properties at any given time. You are unable to sell your housing to the server, so the only people able to buy it off you are other players. The highest amount a house can go for is $1'500'000 and those are few of the Richman houses in LS. Yet the 1.5M price can only be set by players, by default most of the expensive houses cost from 500k-1.3M. At the moment of writing this, most of those houses have been already bought and won't be for sale any time soon, since the players that own them are quite active.
Once you have purchased a house, you can upgrade it with various small things such as a safe and better security as well as insurance. If you can buy a house for upwards of 100k, the prices of these upgrades are pretty much nothing, since they range from around 1k-9k.
2) Transport
Currently the only type of transport you can get is land transport AKA cars and motorcycles. These vehicles can cost up to 140k which is the most expensive car, the Infernus. The money for the cars isn't really all that hard to get, but the levels are, since, for example, the infernus requires level 99 to be able to purchase it. The thing is by the time someone is level 99 they can purchase 10+ infernuses. (Assuming they didn't waste their money on dumb shit)
Cars are super cheap compared to the levels of when you unlock them and how they overall perform. Even the level 35 Banshee can outrun 80% of cop vehicles and it's only 40k.
3) Weaponry
Weapons are quite decently priced compared to their unlock levels and use. The income of both cops and criminals matches quite well. Usually you can live quite a long while just by buying 2k worth of UZI ammo and some armor (or find it in the cities if you know where to look). In situational times you might wanna get a sniper or an M4.
4) Useful/Useless items from stores etc.
This section includes random items such as condoms from sex shops, bats etc. These items cost next to nothing and most of the time are absolutely useless.
5) Wealth Tax
So wealth tax only starts to show up on your paydays after you have 1 million. At this point your tax is around 5k, but since you have so much money in the bank you also get around 2-3k in interest, so you only pay around 2-3k in taxes per million you have, which is almost nothing. You can make 3k in robbing like 3-5 stores in a matter of minutes. At one point I had 3 or 4 mil in the bank and I paid around 15k in taxes, which as I've said before can easily be made back in a matter of minutes.
That's pretty much it. People run around with tens of millions of dollars since there's no real place to invest it in, houses have a cap and aren't all that useful, cars have a limit and are dirt cheap. There's cash coming in the server faster then it can be spent. Please check this out and think about it seriously.