There are always a zillion reasons not to. I myself had a huge list...
But fuck the list and do what you want.
Yes it is scary but its worth it and guess what, hair grows. So worst case scenario you just grow it out.
I just cut most of my hair off. Did I wake up the next morning in shock, yes but I've grown to like it more and more everyday. So much so that I think i'll go even shorter for my next cut. If the idea of going zero to pixie is too much for you then cut your hair in stages. Try out a few looks along the way, ease into it. However there is something very satisfying about a nice swift chop.
|This is what my hair looked like before|
I thought about this cut for way too long. I really thought to be attractive was to have long hair. I made my hair into a weird security blanket and didn't want to give it up. But I needed a change and don't regret it at all.
So again if your thinking about it just dive in. Short hair is beautiful and fun and not forever. Have fun with your look and your style. Don't be afraid to be different or to try something new.