Being gay is a concrete term. Being gay does mean to have a same sex attraction. The word is recognized in the LGBTQ+ community as well as the world. Therefore, it must be a term.
In terms of a committed identity or experimentation, "gay" only applies to people who identify that way. Any person who is straight can have sexual experiences with someone of the same sex.
It’s not a committed identity because the person just wants to have fun. Someone who is gay takes the time to see if that’s their true selves.
The reason why people who are gay become bisexual or other sexualities is because they realize their sexual preferences go outside of being gay. There’s a big difference between being curious about having an attraction, and owning that the attraction is truly a characteristic of one’s self. Sometimes it takes a long time to find out what one’s true identity is.