Is it stupid to spend a lot of money on notebooks?

It's not stupid if you can afford it. Anyoned who judges you for liking nice stuff should just go fuck themselves.

I think you shouldn't pay more just for the aspect. The utility matters

I keep all my notebooks so I think a good quality one is a nice investment. Who wants a bunch of legal pads laying around.

Not stupid unless you don't use them.

Notebooks are a worthwhile investment. You don't have to tell anyone what you paid for them, just saying.