1) Younger people are cheaper to hire in the first place
2) They often have fewer commitments, so more time to dedicate to work
3) They have less experience in the workforce, so easier to bamboozle
4) A lot of them have that fresh excitement and desire to join a “mission” and/or replace through work the peer group they miss from college (which combines well with point 3)
Most companies need very few actually smart people, not sure where the misconception comes from. They mostly need grunts to put in the hours and who won’t complain about their lot.
#) Young people are very susceptible to outsourcing decisions (and morality) to their leadership.
Competent people lose their innate tolerance for self-serving (or immoral) decision makers over time; once you have the breadth of knowledge and experience “to see through that nonsense”, your leadership will be forced to either improve or get rid of their antagonists. Fortunately for leadership, age-related terms are rarely prosecuted successfully in tech due in large part to the absence of unions, and the penalties if convicted are typically pocket change compared to the alternatives.