Okay, so let me guess. This guy is too toxic to be in a guild, to raid, pvp and do M+ with friends, so he is stuck pugging for groups.
He can't deal with losing/wiping and believes himself an elite player, despite not setting foot in Mythic raiding whatsoever this expansion. Maybe in a distant past.
He is blaming his losing/wiping on his teammates having gear that is somewhat better than he expected, but not managing the difficulty he believes he should.
People around your item level, are people that are managing the same content as you. If you're failing to outrise them, it's because you are one of them. Which I am sure your accomplishments reflect.