No, this is not about how people choose to simply live their lives. When the left starts using this nonsense to implement policy, such as allowing men into women's bathroom, it impacts people who otherwise wouldn't care. The left is literally trying to teach children that biology and sex aren't related and boys can be girls and vice versa.
If you want to pretend your're the opposite sex or some made-up gender, I could care less, but when you start trying to flip society around by claiming people can pick their gender and everyone must submit to the another's mental illness, it becomes a problem.