this is the most stupid thing to get mad over, like im pretty sure the only people that get genuinely mad at this are the same kind of people who call themselves gay just to feel special, instead of actually meaning it
well think about it like this, all the people who are gay because they actually
are gay get oppressed politically for the past century, then this joke pride day comes out completely mocking peoples struggles
of course the lgbt crowd is going to be at least somewhat upset. some people are, of course, over reacting, but man are just annoyed by the fact that people are mocking them.
moreover, the base of this holiday is more negative than positive. if it was funny, like going: "straight pride day lol" as a joke, then it would be totally okay - anyone getting annoyed by it would be over reacting. however, this holiday was based on 90's opposition to the gay pride movement (
http://www.nydailynews.com/life-style/happy-heteroloveual-pride-day-article-1.2692558) which is why several people aren't very happy.
of course, most of the people upset by it probably haven't even looked at the news or know the base behind it, and are just trying to find a reason to be upset.