I think for a lot of these people what's 'wrong' with being white and middle class is that, rightly, there is now a much greater awareness of the privilege you obtain from the combination of those two particular characteristics, and that means oftentimes those voices now don't carry as much weight in conversations on things like gender and class. Don't forget that a lot of these liberal 'progressive' types are people who have never wanted for anything or been told no - these days, we are much better at identifying that these kinds of people might be out of touch if they've always lived such a life, and we want to hear from other people with more relevant life experiences instead. Most of us think that's a good thing, but for those who don't get to dominate these conversations anymore, obviously it isn't. So, simply call yourself something where you have to do absolutely nothing to evidence it - non-binary, to an extent bisexual* as well now - ta dah! Now you're ~ different, now you're ~ queer and a ~ marginalised group and suddenly your voice has weight again. Tbh I think it is extremely transparent and I'm surprised so many people are taken in by it. I would love to see a demographic breakdown of those who say they're trans without seeking to medically transition, non-binary, etc etc. I think it would be veryyyyy telling.
*NB not saying here that bisexuals don't exist, or that all bisexuals do this - rather it is clearly disadvantageous for genuine bisexuals that there are people who will use that sexuality to become different - all I mean is that nobody will say for example 'you're not bisexual because you haven't had a relationship with both a man and a woman' so, if you were so inclined, you could 'come out' as bisexual and be taken at face value in order to become 'special and different'. People like Jameela Jamil who are married/in long term relationships with men, but bangs on about being 'queer' and forces herself to the front of conversations off the back of that. Obviously, this damages how people perceive actual bisexuals, but these types don't care about that.