There is always risk trading any stocks. Some of the most solid companies over the decades like AIG went bust during the last recession and investors lost big time. 3X ETFs like UGAZ are even more risky than common stocks.
All I can say is it ain't over til it's over for UGAZ. 3 months of winter lie ahead. Keep in mind that some traders may have sold all or some of their UGAZ positions from the $10s range accumulated in October for profit in November when UGAZ went over $18.