It matters to those who fought hard for their rights of equality in society. It doesn't mean anything to you, but to someone else, it means everything.
Gay pride means little to society these days, as the majority of rights issues were fought and won long ago by the gay community and its activists. Of course, there are some which continue to be fought (e.g. marriage).
It's through this battle that gay pride as developed: that is why it's still celebrated, and they have every right to celebrate their fight for equality. If you're half as intelligent as you claim to be, you should know and respect this.
Being straight or gay is not an accompishment, agreed. But for some young teenager who has fought years of his or her life trying to come to terms with who they are and how they will fit in with their friends, family and world around them is a massive battle that people like you never concieve of let alone fight. In this context, it is an achievement for that gay individual.
Heterosexuals have never had to fight for equality the way gay people have, they have never been treated like shit on a societal level. Can you imagine what that feels like? Have you ever been mass persecuted or segregated for something? No, you haven't. So stop making statements you obviously know nothing about.
Don't assume that whatever you think is correct goes for everyone else.
How dare you demoralise these people, what the fuck have they done wrong to you? If I was your parent I'd fucking beat you senseless.