Is it normal to give up on people who don't call you?

So I have a few friends who never call or text me, yet I'm the only one that puts in the effort to call or text them. I let them know that since we're friends, you can call or text me whenever you want. But somehow I don't hear from those friends unless I make contact with them and then they give me the notorious "I'm busy" excuse. Now the way I see it, if we truly are friends, then being busy should not be an excuse. I mean sure we all get so caught up in our personal lives with school, work, family, etc. But if you somehow have the time to call your other friends or hang out at the bar with your drinking buddies, but not initiate any contact with me, then I see a problem with that. If you can't take time from your "busy" schedule just to text me "hi" then I'm done with you. And yes I have in fact told these jokers how I feel about that, and all they do is "Oh I'm sorry I didn't realize how you felt. I'll try to put in more effort." But of course they don't so I just give up on those idiots. Honestly, I'm a good person and I'll be your friend, but if you can't be a friend back and initiate contact with me at least once a while, then I'm moving on to find someone who will.