Does anyone else feel like they're only important when people need them?

Lately I've been wondering if anyone else feels this way.

Sometimes I feel like I'm the "backup" friend. When someone has no one else to talk to or needs help, they come to me. But as soon as they have other people around or things are going well, it's like I disappear from their lives.

I'm not saying friends have to talk every day, but it makes me question whether some friendships are genuine or just based on convenience.

Has anyone else experienced this? If so, how did you deal with it? Did you accept it as part of life, or did you start looking for different kinds of friendships?