People have been killed because they are gay. They are not always protected by hate-crime laws.
People are denied jobs because they are gay. They are denied marriage, adoption privileges, health insurance including their chosen life partners, legal cojoining (such as joint property rights and inheritance) with those life partners. Oh, and they are regarded by many as nasty and perverted and disgusting.
And the only difference between them and other people is, they prefer romantic and sexual partners of the same gender rather than the opposite.
And some people are freaked out by that. Their own experience is that such things don't happen, shouldn't happen. They've been told that, by other people who believe as they do, who fear as they do. And, because they internally (perhaps not even consciously) dehumanize gay people, they want to stamp them out, as abominations before their Lord.
That is why there is a constant struggle for "gay rights".
I have seen huge strides forward on this during my lifetime, as well as several giant steps back. I continue to live, hope and (on the rare occasions I get up off my fat ass) fight for the simple right to live of all people. I have hope that by the time I die, no-one will understand the concept of gay rights, or women's rights, or black rights, because no-one will think of those groups as a separate entity.