So I have just been on Twitter to see that today is #HeterosexualPrideDay apparently! I'm all for being happy with your sexuality and comfortable with who you are. We all should be, otherwise we would never be happy.
The thing is, is that we do not need pride days to celebrate something which is celebrated every single day. Imagine a day to celebrate being white, or able-bodied, or a man. It would just be offensive. It's like 'oh look, we have privilege and we're going to celebrate that.' Heterosexual 'pride' is the default in culture and society. Everybody assumes everybody is straight unless you look 'butch', 'gay', or hang out in a gay club. None of which means you aren't straight, by the way, and those are all stereotypes. So every day for the straight person is them not even thinking about their sexuality, not being scared of being called names, not being scared of being shot, not being scared of not getting a job because of their sexuality. Nobody is going to experience discrimination for being straight.
Here's a little quote which might help: "LGBT liberation day came about because of a culture of discrimination: President Eisenhower issued an executive order in 1953 legalizing the firing of LGBT people. Openly LGBT couples (and people) were not even allowed to publicly gather; those who did were both harassed by civilians and criminalized by police." So gay pride is there for a reason, and came about due to discrimination.
Today, we don't experience that (although, apparently gay people aren't allowed on certain YouTube series because the creators are homophobic, and people get banned on popular Minecraft servers for having words like 'gay' in their usernames. Totally not referring to anything specific here.) but gay people still experience discrimination and hate crimes. People are literally murdered for being gay, and aside from that, people are bullied for being gay, and afraid to come out because they're worried about what will happen. I haven't covered everything there, of course, but those are two important reasons to have gay pride. Straight people don't experience any of that, so why would they need a pride day?
Be proud to be straight every single day, because you won't experience hate for being straight, or discrimination, or being shot dead. But don't give yourself a day to celebrate being straight, because that to me, is just offensive and undermining to gay pride.