I would love to know what you do when you don't feel like acting like an adult or how you escape reality.

Most of the times when I feel overwhelmed, I try to go back in time to read past events. Or just sleep or watch a movie like everyone else.

I can't really recall much of my childhood days, but from the little I can recall, it was mostly bland and monotonous. So, in a way, I can say I've always been "serious".
And as someone who has had to be serious since a long time ago, I agree with you that it does get tiring.

And I don't think Adulthood is a scam. I just believe we all had the wrong notions about what being an adult really is.

But all in all, you're right. We all really need to loosen up and unwind sometimes.