> People in their 20s and 30s now will regret not stamping out ageism when they hit their 40s and 50s, as they inevitably will

The problem is, everyone in their 20s and 30s assumes they'll be gazillionaires by the time they're 40, because of course they're brilliant and hard work always pays off! Ageism is only a factor if you're not smart enough to make a billion by the time you're facing it.