Don’t quote me on this, but it’s the ETNs you have to worry about imploding, not the ETFs. ETNs are basically an IOU from the issuer, and I’ve seen several ETNs blow up over the years, particularly on the high-flying stuff like $VIX tracking ETNs.

Again, I’m not an expert on the subject but I believe the ETFs don’t have much, if any, risk of blowing up. I do recall an issue where DUST & NUGT had to reduce from 3x to 2x leverage a few years back to keep things in balance (since the miners are so volatile) but you may want to do your own DD on the subject.

DUST and ZSL in particular.

Or do they just move up and down based on the miners no matter how the price moves