Simply put: Nonsense
A bit more elaborate: some people have something against people who differ in some way, whether that be in their sexual orientation or handedness or skin colour or the language they speak or the food they eat or the god(s) they worship or the parties they vote for or the places they live or the clothes they wear. This has always been that way and will always be so. Most people harbour some preconceived ideas about those 'others' - yes, you do as well. In most liberal western societies these preconceived ideas are frowned upon by official institutions, especially when it concerns such ideas related to 'protected' identity categories like sexual orientation, race and religion. your statement regarding the supposed mistreatment of that group does not hold any water. It is a lie, an untruth, a distortion of the facts - unless you can prove your claim.
Can you prove it? Show us how your statement is true, in what way everyone treats gays, lesbians and bisexuals badly. Just saying this does not make it true, not even repeating it ad nauseam, not even when it is claimed to be true by academics from the grievance studies departments - especially not when claimed by those academics from those grievance studies departments since they are on an ideological mission.