If you are talking about a 7 day Caribbean cruise, the demographic will be the same as for Celebrity and Princess etc
If you are talking about a 64 day cruise...... you will see many older people. Who else has that amount of time to cruise. Sure some younger people can break away for that long, but the majority of guests will be older people.
If you do not think you an enjoy being with well traveled, intelligent, funny, fun loving, experienced conversationalists (many of whom can dance younger folk under the table), then you should consider cruising on Disney, RCI or whichever other line appeals IMO