I’m not sure what keys you are running but the 14’s and 13’s i get into always have another dps(probably both) doing over 50k. Maybe I’ll see the random 3rd dps doing around 40k. It would be pretty strange if people are doing 40k and less at 15 and above based on what I come across. Maybe its a horde thing?
For me, I put alot of effort into increasing my dps for the content I do. always simming, always referencing guides, swapping out gear, etc. Highest I’ve done overall in a dungeon is 65k. I don’t consider myself a bad player, but I would consider you a good player based on your OP. My point is, there are different kinds of players, and some people aren’t as good as others regardless of their efforts. Myself included. That’s the world. Don’t let it upset you friend. Take a chill pill and have some fun.
I say this because though I’m not that great, I’m pretty darn good compared to my guild raid team. Would I like it if everyone could hit 50k in heroic nyalotha at this point? of course. the runs would be a cake walk. Do they all hit 50k at minimum? no. just how it is. I don’t let it get to me and you could try accepting people are worse than you.