There's a difference between shopping until you drop, and giving the woman you love the occasional gift to show that you love and appreciate her.
Yes, it's not required, you don't _NEED_ expensive jewellery or fancy weddings, but if you have excess money that you are not investing, why not?
On the flipside, I also like getting nice gifts. Don't you?
Just tell someone you love them and do nice things for them and be there for them. It's free.
I'm into mechanical watches. Just because I find them interesting, not for show. I'm not brainwashed, but heck, getting one I really want from someone I love would be close to the ultimate gift. Do I need it? Of course not. Do I expect it? Of course not.
Now you're just being casually sexist. If you want to judge people for how they choose to celebrate their mutual affection that's fine. So diamonds aren't your thing, thanks for sharing. But let's not go down the rabbit hole of litigating one gender's susceptibility over another's.
You should look into getting a therapist to talk through whatever has soured your outlook on life to this point of bitter cynicism.