Because every other form of money is designed to rob you.

Fiat currencies are literally programmed to lose value - that's not a bug, it's the feature. Your government prints more whenever they want to fund wars or bail out their banker friends. Your purchasing power gets diluted while they get richer.

Gold? Try carrying bars across borders or buying coffee with shavings. Good luck with that.

Bitcoin is the first money that can't be inflated away by politicians or confiscated by banks. It's yours, actually yours. No permission needed, no middleman taking a cut.

The real question is: why would you want money that's designed to make you poorer over time?