Why aren't more people interested in Dhamma?
In the Ayacana Sutta (SN 6.1), the Buddha explained that for the masses who are strongly clinging to sensual pleasures and other things like name, fame, wealth, health, relationships etc., it is hard to understand the full depth and breadth of the Dhamma.


  Then, while he was alone and in seclusion, this line of thinking
  arose in his awareness: "This Dhamma that I have attained is deep,
  hard to see, hard to realize, peaceful, refined, beyond the scope of
  conjecture, subtle, to-be-experienced by the wise. But this generation
  delights in attachment, is excited by attachment, enjoys attachment.
  For a generation delighting in attachment, excited by attachment,
  enjoying attachment, this/that conditionality and dependent co-arising
  are hard to see. This state, too, is hard to see: the resolution of
  all fabrications, the relinquishment of all acquisitions, the ending
  of craving; dispassion; cessation; Unbinding. And if I were to teach
  the Dhamma and if others would not understand me, that would be
  tiresome for me, troublesome for me."


And then, most terrifyingly to us:


  As the Blessed One reflected thus, his mind inclined to dwelling at ease, not to teaching the Dhamma.


Fortunately the Buddha was persuaded otherwise:


  There are beings with little dust in their eyes who are falling away because they do not hear the Dhamma. There will be those who will understand the Dhamma.