The practice to awakening odds are pretty poor. If you were to ask your fellow practitioners how many of them felt as if they fully grasped (experienced) the teacher's teaching, I'd be shocked if more than 1 out of 20 said yes.

Add to that the fact that practice in the Buddhist world is almost always an ass kicker of the highest order (hello screwdriver in the knees), then one wonders why take it up in the first place? The whole process seems a bit like the Christian, "yours is not to reason why"; i.e. it will become clear(er) later.

Saying that, I did meet someone who awakened without a teacher. I suggested that he attend a couple of sitting groups that I used to go to. After the Dharma talk/discussion at each group, without having said a word, both teachers came up to him and basically said, how on earth did you do that?

Talking with him later he said he came into this life to awaken; i.e. it wasn't difficult and he was only just scratching the surface.

Pretty rare obviously, but then again, practicing for 5, 10, 20+ years and awakening is also not guaranteed.