> what is the best 'huge AI bust' trade?

There probably isn't one. Sure you can be bold and try to short something, but the market can be irrationel longer than you can stay solvent.

Also the big tech stocks are inflated. But they have been for years and unlike dotcom there is some tangible value behind them.

I think maybe the sane thing to do is reduce tech stocks exposure and go into index funds. But that's always the answer, so that's cheating :)