Not erasure; it’s cool. At least, it’s not a deliberate act of self-erasure IME.
Here’s a few of the many reasons bi people sometimes call themselves “gay:”
Simplicity: lots of people lack a mentally distinct category for bi and think of it as a subset of gay, so if you’re bi you learn to sometimes lean into it just to save time.
The bi-cycle: it’s not unusual for bi folk to experience predominantly same-sex attraction for a while. So they might identify more often as gay for that time, especially if they’re in a same sex relationship.
Brand recognition: bi doesn’t have the history that gay does in public discourse. We were usually just called gay. I’ve never heard a pundit talk about “the bi agenda” on daytime television, for example. So gay is sometimes preferred when we’re connecting with that lived experience.
Not erasure; it’s cool. At least, it’s not a deliberate act of self-erasure IME.
Here’s a few of the many reasons bi people sometimes call themselves “gay:”
Hope that helps ;)