Of existential issues - redux

I posted this quote awhile back and it's worth thinking about again. In speaking of the deeper issues in life, an author writes:

The emotionally mature adult can face up to the complexity and evil of the world. He can bear knowing that he is ignorant. He is content to achieve that which is within his reach. What is possible contents him, even when it falls short of the apparent ideal. No longer so sure of all the answers, or even whether there are answers, he is too busy working to achieve his reasonable goals to torment himself with such overwhelming questions.

We must be grateful, however, that some people cannot escape asking such questions, and seeking answers, for the results of those enterprises have sometimes been great literature, philosophy, theology - to our immeasurable profit.

What then, of the unlucky few where such existential questions torment them so? My conjecture - based on but a limited sample from observation - is that they either reject meaning (in life) or postulate some higher power (very often God) to explain it all.

In the meanwhile, I am reminded to ask: After all the deep thinking, where is the evidence?