I'd say we're middle class. Mortgage free, two holidays a year - one educational one leisure - kids have several hobbies, wife is sahm whilst I'm on 140k. But - state schooled. My dad went to a private school and taught me a lot. The difference is education on softer skills not taught in state schools. I educate my kids on various topics not taught at school - they make the difference across your life:
The drive and want to succeed. Just find a way, research, trial and error, ask for help etc.
Attitude over grades. Be competitive. Not with your peers, but yourself - if you got 7/10 last time , analyse why , look at weaknesses that you can improve, then try and beat your last score. Don't give a shit what others are doing and don't buy into the school "everyone wins" mantra because it's not true. At work , valued assets that get promoted are the ones that deliver. Attitude.
Economics- how to save, how to prioritise spending. How to invest, why you should start snd prioritise your pension, etc etc
Hobbies and staying off social media. The latter is a waste of time and mental health minefield. Our kids have hockey, swimming and theatre clubs, the more active they are the less they bother with tech and stay mentally healthy. Those hobbies also promote social skills, competitive attitude and fitness.
Pay yourself first. Work before play. Muscles are made in the kitchen etc etc.