How do you know, and for better or worse?
Sounds like he might have been acting on wisdom, and at the time you might have perceived him through a lense of naivete, which still holds. I felt similarly in my early twenties in perhaps a similar environment, but now I know all the seniors I'd have resented were decades ahead of me in terms of what they valued and why. Caring about that work was stupid, and I should have just enjoyed my time more.
Their decisions made the life of those around them miserable because they did not care about the consequences of it. Like for example, hiring an intern who had basic programming skills when there was no engineering bandwidth available to support the intern, and then bouncing them around multiple large projects every week, for the sake of showing upper management that they had people "working" on priority tickets. There is more to this story, but it's just more details painting that person in a bad light.
I, most certainly am not such a person.
> Caring about that work was stupid, and I should have just enjoyed my time more.
I agree. It's a work in progress for me to get to that state.