Bisexuality is simply being attracted to two genders. The prefix "bi" means two, and the word "sexuality" pertains to an individuals sexual preference. Nowhere in this term is the word gay. No prefix in the word means "just a phase." Believe it or not, it is possible for an individual to be attracted to more than one gender.
If an individual who labels themselves as bisexual, dates someone of the same gender- it doesn't make them any more or less bisexual, nor does it make them gay. If an individual who labels themselves as bisexual, dates someone of the opposite gender- it doesn't make them any more of less bisexual, nor does it make them straight. If an individual does not accept another human being because of their sexual preference, it doesn't make them any more or less a person, it just makes them an asshole.
Just because a person is bisexual does not mean they are attracted to you. Bisexuals still have types. They might be attracted to two genders, but that doesn't mean they are attracted to every single person. Just because a person is bisexual does not mean they are more likely to cheat on you. Bisexuals are still capable of being in a monogamous relationship. Just because a person is bisexual does not mean they are always up for a threesome. Bisexuals are not just a tool to 'spice up' your heteronormative sex life, bisexuals are human beings- and badass ones at that.
Why does our world find it impossible to celebrate bisexuality? Why does society feel the need to tear down the idea of being attracted to two genders? Why does the media feel the need to portray bisexuals in television as villains? Why does the LGTBQ+ community continuously get so much hate for executing so much love?
There is no definitive reason. I don't have an answer. We live in a world that will always have at least an ounce of hate. So where do we go from here? We keep loving. We keep educating. There is a generation above us who did not grow up in the loving environment that we are continuing to build for our future. Tell them. Tell them about the love that our generation shares. Explain to them how sexuality is a spectrum, just like light and sound. Show them the communities we've built. Motivate them. We may be young but we are powerful. This is our time. This is our world. Utilize it. Live in it.