I have found a few different types of people not interested in LDing, and some of this may be a little surprising.

People that like LDing are normally people that would be called dreamers. They most likely like things like anime fantasy or sci fi because they like to think about things that dont exist. It doesn't bother them that they just read 250 issues of Naruto last night and that these characters don't exist or have any relevance to waking. It is fun. I do it. Simple enough. Prone to day dream, and to want better things in life.

People that want to LD and learn how to (through sites and books). They are similar since they want to LD, but they are normally successful at their hobbies and know what it takes to get good at something. Pay attention to the right people and ignore the wrong ones. Even though they day dream, they still accomplish things in reality and they are normally led to wanting to do something with their life.

People that LD naturally. Normally a little more absorbed in their own world, similar to a child. Either not caring what others think, and just doing what they want to do. Their LDs can seem vague and not as colorful to the non natural, because to them it is another part of life, so the familiarity can bread contempt. They normally get to a point that they always know they are dreaming but dont care to "accomplish" anything, but they will complete the stories that are given them. They are normally go-getters in life and successful in whatever field they are in. Need less time for play because they can play at night (this can be gotten by all LDers of course, but it is easier to reach for naturals. (Might sound a little harsh, but this is what I have seen from most. Some of these things could be considered a plus to a lot of people)

Hipsters. LDing isn't popular. Must like before it gets popular.

People that aren't interested in LD
1) new things are boring. These people just do whatever the world around them does, and since they are into the new normal things like movies and phones. Doesn't really care to have an adventure alone. Won't read books that aren't outside the social ones ( twilight, divergent etc). Imagination is not good.

2) too much work, not enough pay off. This could be the ones that I understand the most. You spend lots of time and for the at least 6 months it seems like most people don't take to it very quickly. Hard to make people get up and do it.'

3) sounds boring. 0_0 I have no insight on this one. it scares me.