But on the other, I do feel bad about the idea of buying new clothing when the ones I have are still in good condition, because that is also consumerist behavior. Will definitely upgrade my wardrobe when I hit the point of having to be taken more seriously.
Just letting you know, you might be interested in donating those clothes to people who need it, and you can even get a tax deduction from it. You can also give them away as hand-me-down items to relatives. Furthermore, you might be interested in wearing them guilt-free in the context of athletics, basically reduce the wardrobe size by 80% but leave the remaining for when you hit the gym.