Sand isn't soft, at least when you land on it.

As young man I tried jumping down a steep dune ~100+ meters tall. My plan was to run, jump and roll all the way down. I got enough speed and air that I was about 2m up, which is high enough even at steep slope landing on sand to knock the wind out of you. And then I rolled, and bounced, and each bounce hurt. It was like whoosh, oww, bounce, owwww, bounce, owwww, etc. Also, sand in every orifice.

Moral victory: I probably lost 60m altitude rolling.