It's people not class. You get arses in all classes, attention seekers, virtue signallers, snobs, etc.
I'm from a traditional northern working class background, father was a shop worker, mother was a secretary. We had no money, never went on holiday, had an ancient car that always broke down, lived in a tiny house, etc. I was best friends with one of our neighbours, father was a solicitor, mother was a SAHM, always had a new car first day of new registration, 2/3 holidays per year, large house, etc. Our parents became friendly because of our friendship. There was never any snobbery, one up-manship etc - they never rubbed our noses in their wealth and lifestyle. My parents were never invited over when they first got a new sofa or a colour TV or a new car - they never did that "show off the new stuff" thing at all. They were very quiet and aware of their lifestyle, and respected our lifestyle. If we went for a day trip to the seaside (our only form of "holiday"), they were always genuinely interested, always asked about it, and never turned the conversation around to showing off about their last skiing holiday or whatever.
As professionals, we consider ourselves middle class, but we're still working class at heart. We do middle class things, like skiing, lots of holidays, cruises, new cars, detached house, etc etc. Most of the people we socialise and work with wouldn't have a clue, because, like my best friends parents', we don't go around showing off or attention seeking. We've never put a single holiday photo on facebook.
My OH has a lifelong friend who is working class through and through. He's got a massive class chip on his shoulders. Always trying to be the big "I am" making himself into something he isn't. Rather than buying an average car, he has to have something special so buys old run down "posh" cars like BMWs, Mercs etc that are so old and past it, they never last more than a few months. The other month his Facebook page was plastered with pictures on a cruise - it turns out he went on a bargain basement 2 night "repositioning" cruise that didn't actually stop anywhere. For weeks afterwards, all he talked about was his cruise, making it out like it was some kind of millionaire's world cruise. My OH has known him so long, he "understands" him and puts up with the bragging etc - it's just a lifetime of insecurity, but he really wishes he would just accept who he is as he is constantly losing friends due to the big "I am" attitude and trying to be something he's not.