快樂牛郎

Buy it now and get burned.

You don't invest in something after the trend has already begun for years.  If you can pull the plug in time, you will still make some money.  But I assume you don't have the holy power.

The most likely scenario is:

you buy it today
get 30% gain in one week
become greedy
double your stake
and lose 80% of that in the next month

快樂牛郎

In addition, these leveraged ETFs have huge erosions.

If you don't get the trend right within a short timeframe, say 3 months, you will get burned even if you get the long trend correctly.