Why are there people in their 30's who refuse to accept they are growing older and still act and dress the same way as they did when young?

REBELLION. It's what teens do and it's fun.
You NEVER age when you're having fun.
The Body may get old, but that is just wear and tear out of good use.
(it happens with New Tires Too, but the car still moves).

If this person were someone important to you, are you saying it would be better that they sit at home and waste away?

I plan to DIE IN THE GAME. If I'm having fun at that point,
I will probably be late to my own funeral.

Those are never fun... even for the living.

I too am approaching 40. 😖 I don't feel it at all. I still feel like I did in my early 20's. I've even been compared to sounding like a teenager. I could care less about growing up and acting mature. Who says just cause you get older you should act older. I am going to act young and have as much fun as I can while my body still allows it. As for dressing your age. I see what men and women my age wear and yuck. No thanks. I'll stick with my ripped jeans and graphic tees.
I think this guy probably feels the same as me. Either feels youthful it is at least trying to hang on to his youth. Plus you know men don't ever mature right?