In principle, yes. A 3× fund loses about 3% for every 1% its index falls in a day, so a one‑day index fall of about a third would wipe out the fund before the next reset. A 2× fund would need a one‑day fall of half. The TQQQ prospectus says that if the Nasdaq‑100 approaches a 33% loss at any point in the day, “you could lose your entire investment.”
Nothing close happened in this window: the S&P 500’s worst day since mid‑2016 was −10.9%, on Mar 16, 2020. The realistic path toward zero is slower: a long, volatile decline that leaves too little to recover. SOXL lost 90.5% from Dec 2021 to Oct 2022. The −3× Nasdaq‑100 fund SQQQ lost more than 99.9% of its value over the whole period, because the index it bets against rose; inverse funds decay the same way (see inverse ETFs for hedging).
That is why investors who hold leveraged funds through crashes usually decide in advance how much they can lose, and when they will step aside: see when it is safe to hold leveraged ETFs.