Nobody on the left is saying that a man can become a woman
Transgender people are not asking for special treatment and they're not even asking for attention, they just want to be left alone to live their lives. But conservatives can't stop harassing them and talking about them and accusing them of things they aren't doing, like preying on children.
If you have a problem with addressing somebody the way they want to be addressed and being respectful of other people, that's your problem. If you're a man and somebody insists on calling you a woman or calling you by the wrong name, that's disrespectful and most people wouldn't like that. And yet conservatives do that every day to transgender people. They treat them in a way that they would not want to be treated themselves. That shows a disturbing lack of empathy.