Why do people have to come to terms with the fact that they're not straight?

There is still tremendous stigma in the world - including the US - directed at gays, bisexuals and transgender people. Some states allow housing discrimination and loss of employment based on this discrimination. Hate crimes still occur every single day. Religious intolerance abounds, laws are still on the books against same sex relations. Social isolation is a real thing. There are still discrimination cases being decided in the Supreme Court. There are still organizations that can take a teen and force him into conversion therapy against his will.

If you've ever faced any of this stigma and discrimination, you can answer your own question.