I believe the available evidence suggests that over the long term, a small amount of leverage increases returns. Obviously it increases volatility as well, but if your time horizon is long, you can cope with that.
You do not want to invest in ETFs that are themselves leveraged & rebalance daily however, that’s going to eat all your money if you hold them for any length of time - those products are designed to be held for short periods only.
The expense ratios of leveraged ETFs are nothing compared to the volatility drag. There are far cheaper and more effective ways than leveraged ETFs for buy-and-hold investors to obtain leverage, notably LEAPs and index futures. (Disclaimer: Not investing advice, do your own research, etc.)
You do not want to invest in ETFs that are themselves leveraged & rebalance daily however, that’s going to eat all your money if you hold them for any length of time - those products are designed to be held for short periods only.