Many people have pretended that making random jokes about a trans person isnt harmful.
When you make fun of a person, you tell them and the world that you see them as less than a person, justifying those who would like to treat these people as less than.
When those offended/hurt/otherwise people speak out, asking to be treated as equals and people scoff at this, you make it clear you have no regard for this persons well being.
Making suggestions about the mental health of these individuals and the what not, you feed into hate culture.
Every time you stand back while someone puts down another person, and every time you do the same,you are the problem.
Put yourself in the shoes of everyone you meet and think again.