Why do people answer questions that doesnt concern them?

because you ask.

Even better is when someone starts commenting on a answer they didn't write. That's when you know it's going to be good.

idk, maybe to rack up coins. Gifts are expensive.

I was going to answer but this doesn't concern me.

Because it's there.

Boredom

Why not? Wait, does this concern us?

they think it concerns them

That's my business- not yours (har har)

I suppose that's why people use sites like this. To join in and be a part of a small community and answering questions is a part of it.

Bored

Especially if they're just gonna be rude, or act like they don't want to answer despite getting involved

Yep Boredom