You could short publicly-traded PE firms with unfavorable profiles, go after companies with bad current ratios and operational cashflow, or just short the market. Dangerous game, though — remember that the market can stay irrational longer than you can stay solvent.
First, watch The Big Short and decide how you'll manage being on the right end of a winning bet with the incumbents doing everything they can to screw you out of payment.
Actually, this is my favorite answer, because it’s absolutely THE way to profit from terrible economic practices. Borrow money, and never give it back. That IS the correct way to come out a winner when it comes to operating stock ownership.
Be the borrower.
Other people’s money, as they say. But can you spend that money as is on for example a Ferrari? Best bet would be to “invest” in something high risk where you either lose it or make so much you can pay off the loan and still be loaded.
You can short or buy puts on high yield ETFs, such as HYG and there are probably some others. However, unless you know what you're doing, and have risk management, it's probably not advisable to hold longer duration short positions. The market may ultimately go down, but in the mean time, you'll be losing money and may not profit very much when it ultimately does go down.
The short squeeze in HYG over the past few weeks is insane, up nearly 6%. It had moved +/- 1% all year up until then. You’d have to hold through price moves like that.
