With leveraged ETFs you are preventing blowup (margin call), since the index would have to go down 50% or 33% in a single day. The "time decay" or "leverage trap" is overstated by greedy brokers, who want you to margin your accounts.
It's clear you don't know how leveraged ETFs actually work. Pull up some long term charts of some leveraged pairs and you'll see.
Right, if you had bought the FAS/FAZ pair last November, you'd be down only about -83% by now. No big deal, eh?
If you bought the equivalent ETF (or its individual shares) on portfolio margin to leverage 3:1 you would have gotten a margin call (posibly even owing money to the broker). What you prefer 17% left, or losing-it-all/owing money?
Uhmmm.... how about not holding a highly leveraged instrument for a long time through while losing money? And while we're at it, how about trading with size that is appropriate for your account? If you're getting margin calls, you don't have a clue what you're doing.
For those who decide to use leverage, leveraged ETFs are far safer. You can reduce exposure, placing only a third of your account (thus only risking about 30%) in a 3X ETF.
In reducing your exposure you are adding a lot of risk. 33.3% of equity in a 3x ETF IS NOT EQUAL TO: 100% of equity in SPY