What do you mean you 'don't believe in it'?
Menopause is a fixed point - 12 months after your last period. Peri is just the term for transitional period leading up to it where hormones fluctuate.
I don't understand what you think there is to be believed in or not 😕
I'm mid 40's and started to notice changes about 18 months ago. It's great that women are talking about it. I've had so many conversations with women of a similar age who all say they can't believe no-one told them about what might happen - night sweats, weight gain, loss of strength, insomnia, brain fog!
I think we would all agree that it is important to talk to girls about periods and what to expect to prepare them for it. We all also know that women's experiences of menstruation vary wildly - I personally have always had it really easy, but am quite capable of understanding that other women can suffer quite badly from heavier periods, PCOS, endo, etc. I don't take my experience as being 'the norm' and know a lot of these issues are not talked about nearly enough.
So why is perimenopause and menopause different? It's all part and parcel of the same process - it's great that it is getting talked about more now and that women are able to understand that they are not alone in experiencing some of the difficulties that come with it, and what they might expect if they are not there yet.
Just as some women sail through periods their whole life, while others struggle, some women will sail through peri and for others it will be hell. Just like some girls start their periods at 8 or 9 and others at 16, some women will start peri in their late 30's or early 40's and it will last 10 or more years, others may not start peri until their late 40's and hit menopause three or four years later.
Seems like an odd thing to be judgey about to be fair.