If you're making big money at 18, you should be saving every penny you can in tax-advantaged retirement accounts. (If your employer offers it, see if you can do a Roth 401(k), as odds are good you'll be in a higher tax bracket at retirement than you are now and you will benefit from the Roth structure. Otherwise, use a regular 401(k). IRAs are also an option, but you can put more money into a 401(k) than you can into an IRA.) If you do this for a decade or two while you're young, you'll be very well set on the road to retirement. Moreover, since you think "I've got the money, why not?" this will actually keep the money from you so you can do a better job of avoiding that question.
Your next concern will be post-tax money. You're going to be splitting this between three basic sorts of places: just plain spending it, saving/investing it in bank accounts and stock markets, or purchasing some other form of capital which will save you money or provide you with some useful capability that's worth money (e.g. owning a condo/house will help you save on rent - and you don't have to pay income taxes on that savings!)
18 is generally a little young to be setting down and buying a house, though, so you should probably look at saving money for a while instead. Open an account at Vanguard or a similar institution and buy some simple index funds. (The index funds have lower turnover, which is probably better for your unsheltered accounts, and you don't need to spend a bunch of money on mutual fund expense ratios, or spend a lot of time making a second career out of stock-picking). If you save a lot of your money for retirement now, you won't have to save as much later, and will have more income to spend on a house, so it'll all work out.
Whatever you do, you shouldn't blow a bunch of money on a really fancy new car. You might consider a pretty-nice slightly-used car, but the first year of car ownership is distressingly close to just throwing your money away, and fancy cars only make it that much worse.
You should also try to have some fun and interesting experiences while you're still young. It's okay to spend some money on them. Don't waste money flying first-class or spend tooo much money dining out, but fun/interesting/different experiences will serve you well throughout your life. (By contrast, routine luxury may not be worth it.)