ELI5- Why can’t an individual remain constantly in a state of euphoria or high? Why does everything eventually return to normal?

Question

I just had this random thought while lying on my roof, listening to “Young Dumb & Broke,” and being in that same state.

In: Other

Answer 1

“sunny days wouldn’t feel special if it wasn’t for rain, joy wouldn’t feel so good if it wasn’t for pain” – 50 cent