Because I'd never be approved for adoption and I'd constantly be accused of being a pedophile even if I was.
There is a huge cultural bias against men taking care of children.
I've even been on dates, and been told my interest in having/adopting children makes me creepy. I've always wanted marriage/children, but most of my female partners over the years this makes me defective and undesirable, and most of them 100% hated children.
Further, I knew quite a few adopted kids growing up. And they all were very problematic and hated their parents.