Why do people be downvoting?

Okay I’m not gonna lie. If someone comments on my post saying rude things, the petty side of me takes that out by downvoting their future posts.

I have seen some of my pictures on the daily rehome post have -2 downvotes. It’s just pictures of what I’m trying to sell, with my nameplate mind you. Are yall being petty like I am or something? 😂

What are some reasons y’all downvote people (outside of the obvious like if they are a scammer)?