It used to be that so many gay people were in the closet and participating in their own subjugation (Some people are still doing this) and its really easy to discriminate a group that doesn't appear to exist. Some other gay people who DIDN'T want to be thought of as in the closet started dramatically parading themselves so people could see they exist... and that started the tradition of the gay pride parade.
The invisibility thing is mostly gone now but you have to remember that gay people in many countries are still treated unequally and that there's considered to be something wrong with us.. The gay pride parade is an affirmation of pride in yourself.. straight people aren't treated unequally or flawed.. thus no reason to have a straight pride parade.







