What you are seeing in the above picture is "history," so to speak. According to Unicorn Booty:
In 2015, Anthony Rebello promised to celebrate heterosexuality by holding a massive straight pride parade in Seattle. He invited thousands of people via Facebook, writing: “In the name of equality & equal rights, I have created this event to celebrate our right to be heterosexual, and to encourage younger heterosexuals that they should be proud of their heterosexuality.”
. . . The parade was held on July 25, 2015. Rebello clutched a bunch of black and white balloons and a “STRAiGhT Pride” sign made of a ragged chunk of cardboard. Proudly clad in the traditional heterosexual male garb of ill-fitting pants, a rumpled T-shirt and an unflattering hat, Rebello marched on Seattle’s Capitol Hill, alone, and we mean alone—literally no one else joined the parade.
Believe it or not, there have actually been six cases of heterosexuals attempting to initiate "straight" pride parades and flopping miserably. Unicorn Booty has catalogued them all in A Short, Stupid History of Straight Pride Parades.