You arent wrong, it is quite easy to get carried away, especially when you know that is their central source of insecurity so they will react extremely aggressively since in a sense I am denying like you said their perceived superiority and eliteness upon which their self worth is based.
I am honestly not certain either if there's a solution to an elitist mentality that doesnt involve months of extremely friendly and painfully positive therapy level talk because humans cannot simply rearrange their core belief system no mater how wrong it might be in any small amount of time.
Negating their egos is definitely a task that is pretty hard, especially as a random forum poster though that is why I ended up really liking the idea of trust system and imagined a possible expansion of it that would lead to high end content as a form of solo challenge by having it tuned that in order to be beaten it would require perfect mechanics and decent dps performance, if that were ever to be true we would see countless casuals, solo players and those people they demean(By implying they are bad because they havent done high end content) beaten their precious high end content and getting those rewards.
Suddenly the one thing they hold above all others vanishes and they will be forced to finally accept that the real challenge and actual difficulty of high end group content is finding the right people aka the social barrier many dont want to bother with, not their l33t performance they obsess over, alas that is something that the devs would need to do, not me.
Though the general principle would be something that proves that those casual solo players arent the terribad, low skilled, lazy, incompetent people and other generalizations they throw around but unless trusts get expanded I am absolutely certain they will always demean solo achievements as inferior to their group achievements even when the personal skill required in those achievements might be higher.