Why Resign?

So many people resign their games when they are down material.

Why not just play on and try to win? It is possible that your opponent might make a mistake, and you draw, or it could be stalemate. You never know, your opponent might throw away there queen on the next move and then they might be resigning. 

It makes sense to resign if you are in an arena tournament and you want to fit in a few more games so when you see that they will be checkmating you in a few moves- That is the time to resign.

Other than that I just can't think of any times that you would choose to resign and not just play on. I have won so many games by just playing on and not resigning when I was down by loads of material.

Comment down below if you can think of any other situations where you would want to resign, and thanks for reading

Edit: A friend told me that the reason that they resign is because they don't want to suffer