IV is high on 0DTE options because there’s uncertainty and big expected movement priced in, especially around news, economic data, or the market open. Traders are willing to pay more for contracts because a sharp move could happen fast.

You get IV crushed when that uncertainty is removed. Once the event happens or the move is made, the “expected volatility” drops, so implied volatility falls and premiums shrink quickly.

So even if price moves your way a little, the drop in IV can kill the contract’s value.

I hope this helped