What kind of person leaves without saying goodbye?
Ghosting—aka the Irish goodbye, the French exit, and any number of other vaguely ethnophobic terms—refers to leaving a social gathering without saying your farewells. One moment you're at the bar, or the house party, or the Sunday morning wedding brunch. The next moment you're gone.
Is it rude to leave without saying goodbye?
No, it is not rude, especially since there is a good chance you do not know all 200 of them anyway. I think the general rule of etiquette is to make an effort to say goodbye to the host/hostess and thank them for the invitation and time.
What does goodbye for now mean?
Bye for now means you hope to see them again. See you later, is the same intent. Bye is goodbye for good. Bye for now means you hope to see them again. See you later, is the same intent.