The answer is: because
Our first "real" cruise was a Hurtigruten winter cruise up the Norwegian coast (Bergen in the south to Kirkenes all the way north, near the Russian border). It was our honeymoon, thus we went for "comfort" - booked a minisuite (only pullman beds / sofabeds in "cheaper" cabins, queen beds only start at minisuite level), went for one of the newer, more "luxurious" ships (M/S Trollfjord), spent a night in a hotel before/after the trip.
Unfortunately, as soon as you join "the" Hurtigruten discussion board. That means you are a snob. From "their" view, you are only supposed to book on the old classic ships (from the 50s!) and spend your days in the least expensive inside cabin as it's all about the scenery and "the real cruising experience", not about comfort. You spend your nights in a hostel or the least expensive hotel that is to be found. Also, you have to travel during winter to experience winter storms.
"Luxury" still means no casino, no pool, two hot tubs, no roomservice, no shows (very few, very interesting lectures though), no bingo, and the minisuite most likely equals a regular ocean view cabin on most major cruiselines... and you still spend at least as much as you would for a
Disney cruise (our minisuite would cost nearly $9000 in August this year, winter is a lot cheaper though). As soon as you mention that you can imagine one day traveling on a "real cruiseline"... oh well, you better don't. You snob.

[Yes yes, I am generalizing - I know!

]
I assume sometimes it's envy.
Sometimes it's the problem of not accepting that other people may have other opinions. (Tragic *sigh*)
Sometimes it's pretending to agree to what you think is expected of you (as member of the general population, not trying to stick out).
Sometimes it's making someone feel bad about their choices just to make yourself feel better.
Some people are just mean spirited.
I stopped making excuses for myself and started accepting that... I can't help it! People will always talk (and I'd rather have them talk to me then about me behind my back).
We are now looking at
DCL for our next cruise. It boils down to a combination of experience/style/itinerary. I know that most of my friends/family won't understand that decision if we go through with it. I can accept that. They won't understand why Disney, why a TA, why travel to the US at all, why spend all that money

just go to a nice all-inclusive resort in Turkey. Or on a nice city trip (staying in a hostel of course and don't go out for dinner!). That's the way it is. You can only make yourself happy, not everybody else.
Rant over *lol*
No really. We love to travel. We do have a lot of vacation. We don't travel much but if we do, we want to relax. I rather book a nice hotel and only travel once a year than traveling cheap five times a year. We accept everybody who wants to and we have traveled that way, too (and enjoyed it). We have seen too many people die far too young than to move everything to when we retire (in 35 years). Different people, different priorities. Each to his own.