Because they are predatory males, and degenerate coomers. They see being a woman as fulfilling a fetish, or giving them some leeway towards being able to have their way with women or children. Most cis women don't behave in any way like troons. For one thing they are brought up to be more wary of men in general and being in certain areas at certain times, or just putting themselves in places where they could get attention at any time, because just about any man could physically overpower them and rape and/or kill them if they wanted to. Cis women also spend a LONG ass time getting clean, doing their hair, putting on makeup, choosing the right outfit etc. and most troons could never understand the time and effort women must put in to look nice. They don't understand and even if they did most would not want to put in the effort it would take for them to learn how to act and behave like a woman.