If he'd over revved the car a few times, or dropped a gear and blew the engine, that's a stupid thing... To sit there for minutes on end aimlessly bouncing off the limiter in a public place really shouts he shouldn't be allowed in a car, god knows how ridiculously he drives if he has absolutely no mechanical sympathy like that. One less of those on the road makes me happier tbh.
I guess you haven't been 18/19 for a very long time.
Being young is not a justification for doing stupid things (Read: being a bell end), its an excuse and a lame one at that. You say "people do stupid things", I'm afraid they don't, You'll find that
stupid people do stupid things, they can't help themselves, they're dim witted, it is in their DNA.
I doubt he will embarrassed by this at all and next week he will be found standing in another Supermarket car park goading another similarly monosyllabic, hoody wearing yoof to rev the nuts out of his 15 year Saxo and regaling them with the story of the fire and how he received his ASBO and/or TAG.
Oh happy days!!