Honest answer:

Because they are an abomination, a physical manifestation of our decaying society and a symbolism/result of our inability to say, "No! This is wrong!" These transgender freaks are suffering from literal mental illnesses which cause them to believe they are the opposite gender. Delusions should never be encouraged, only dealt with responsibly through therapy and medications.

I honestly believe that 95% of these trannies are the result of surpressed childhood sexual trauma. The other 5% are LARPing to get in the little girls room.