Companies can raise prices and avoid the effects of inflation so equities will continue to rise, while cash deflates in value. Real estate values keep pace with inflation, generally speaking. Any borrowed money can be paid back cheaper (debt devalues with inflation) which helps anyone who is leveraged on their investments crank up the ROI even more. I’m sure I could come up with more but those are the main three that came to mind.

FWIW, 98% of my net worth is in stocks, the other 2% is cash