Again, I don't deny the existence of trans people. They exist. I think it is real. But a biological male who believes themself to be a woman, is a biological male, even if they express their gender as female. I'll call that person whatever they want to be called--he, she, it, whatever--and I won't fire them, evict them, or exclude them from a place of public accommodation based on their trans status--because I don't really care how my employees, tenants, or customers want to live their life or express their gender/sexuality--but it doesn't change the fact they are a biological male.
And, more pertinent to the topic, when a biological male hits puberty, that person's body undergoes changes that make that person bigger, faster, and stronger than the person would otherwise be. Thus, that person should compete athletically against other biological males, whose bodies have undergone the same changes. No one is saying that biological males can't compete. They just have to compete against other biological males--whose bodies have undergone the same changes--so there isn't an unfair advantage. Otherwise, why do we even bother with women's sports? If sex is a continuum, we should just have jv and varsity and be done with it.
It is mind-blowing to me that this view is controversial, but I think that says more about the makeup of the regular posters on this board than it does about the merits of the idea.