Players that think that they know what they are doing.

Pride and lack of self-awareness aren't close friends with learning. What he wrote goes hand in hand with his rating.

How do you know they aren't a mastermind? A number isn't everything.

We lost.

Why did he say your a bad player though? 

Just ignore them. Sometimes if I don't play the moves my team mate points out, they will usually say you are stupid and should give up living (or something along those lines). Just keep playing.

I tried to give him a suggestion.

I had this one guy with a significantly higher rating than me call me dumb.

Few minutes later, I checkmated him (Yellow) and Blue and ended up winning by ~10 points