Well, I guess I'm one of those self and lazy people...
My wife and I love cruises. We go on cruises all the time despite we are in our mid-40's. We took our first cruise about 18 years ago with family and fell in love with it. We usually get a cabin with a balcony. I have to admit that we are lazy. With a cruise ship, you have a hotel and a restaurant traveling together with you. To us, that's very convenient. And yes, that's because we are lazy. AND also cheap! For a relatively reasonable price, we get decent food and board.
I'm not so sure about the "selfish" part though... Cooking food, finding accommodation and entertainment ourselves seem to be the things we have been doing everyday at home... On a cruise, for about 5-7 days, we would like to forget about all these things and just get pampered and enjoy ourselves. I would like my vacation to be stress-free so that we can relax, enjoy what we cannot at home and do something different for once. It sounds like a good deal to us, at least.
I have to admit that we are not as cultured as some others. My wife and I seem to care less about experiencing different cultures and education. Let's face it, both of us have spent 2/3 of our lives getting formal education and continuously getting additional education of all sorts everyday at work and at home. We can skip some of that for a week out of 4-5 years (yes, that's how often we take vacation. Pathetic? Yes...). We seem to care more about de-stressing, maybe because we have been under so much stress and pressure at work... It seems that, nowadays, our dream day would be a whole day of doing nothing at all. A cruise trip lets us do just that... Going to bed whenever we want, waking up whenever we want, eat whenever and whatever we want, taking a nap whenever we want, AND doing nothing else. It seems to be a luxury for us nowadays...