When son graduated HS, we bought him some stereo gear. When daughter graduated, she got a laptop (used, but nice). When kids turned 21, we threw them a party. Side note: daughter got falling down drunk at her's and fell down! Leg was out of action for a month.
When I graduated HS, folks threw a party. When I turned 21, they threw another party (any excuse for a get-together). Of course all my friends bought me presents of whatever wine was selling for $1.259 a gallon. Heck, most didn't figure I'd make it to 21.