There are arguments to be made, especially if you're young and just starting out to take a reasonable amount of margin and kickstart your compounding growth.

Say you just started working, have no use for your money and are willing to bet 20k on index funds vs a 90% market drop, you should be able to take 2k in leverage and set up your position be auto closed.

But of course as you have more money this type of market exposure starts shifting as you have shorter timer horizons to rebuild and are instead going into more of a wealth conservation mode.