I do that but I also feel kinda bad since I feel I’m taking it instead of someone else who’s more budget constrained than me

You're providing income to someone whose almost definitely more constrained than you. Without you, no one may have bought it. And the other comment is right - it's a buyers market, we need more buyers, there's a surplus of sellers. Another thing - if sellers more quickly and more easily get to sell their stuff second hand thanks to you, they're more incentivized to sell more in the future as well instead of keeping it in a drawer or throwing it in the trash.

You're doing great for everyone involved!

You shouldn't, really. I don't think there's shortage in the second hand market. We probably need more people reusing stuff.