Why is Buddhism a venture of a limited few? This question is further to my last question on Nirvana and evolution, and considering the answer... If we believe the Buddhist cosmology to be true and Nirvana as an evolutionary next step, then why is it that very few people actually tread the path to it?
Considering the world religious demographics only 7% of worlds population follow Buddhism and of those who call themselves Buddhists maybe just 1% actually want or strive towards Nirvana.
Is intense suffering an inevitable step to begin striving towards Nirvana? If Buddhist understanding of the human condition and psychology is true, why do only a limited few humans want or strive towards Nirvana? If Buddhist cosmology is true, why do humans not en masse go on the Buddhist path?
The Buddha once asked himself much the same. And in his question, we catch a glimpse of why there are a limited few. Indeed, the Buddha first thought that there were none:

SN6.1:1.4: “This principle I have discovered is deep, hard to see, hard to understand, peaceful, sublime, beyond the scope of reason, subtle, comprehensible to the astute.
But people like attachment, they love it and enjoy it.
It’s hard for them to see this thing; that is, specific conditionality, dependent origination.
It’s also hard for them to see this thing; that is, the stilling of all activities, the letting go of all attachments, the ending of craving, fading away, cessation, extinguishment.
And if I were to teach this principle, others might not understand me, which would be wearying and troublesome for me.”

Fortunately for us, Brahmā Sahampati swooped to the rescue, proclaiming:

SN6.1:5.5: “Sir, let the Blessed One teach the Dhamma! Let the Holy One teach the Dhamma!
There are beings with little dust in their eyes. They’re in decline because they haven’t heard the teaching.
There will be those who understand the teaching!”

So the Buddha looked and saw that there were indeed a few with little dust in their eyes.
It's not so much the intensity of suffering that inspires one on the path. It is the sheer inevitability of suffering in even the smallest relishing. Everybody else is looking exhaustively for exceptions to the understanding that:

MN1:172-194.26: ...relishing is the root of suffering,

There are no exceptions.