There are lots of reasons. Some people want answers for questions that we don't have scientific answers for yet, or that science can't possibly answer.
Some people want to use a framework to justify their behavior.
Some people are scared or disgusted by the implications of our knowledge, and they want it to be something different.
Some people want to manipulate others.
There are many religions because there are many reason why they exist.
One problem is trying to discern people who have truly religious beliefs, vs. people that are lazy lairs.
I think Trump supporters that talk of him being chosen by God are lazy lairs. They have a racist world view, can't justify it, so bring God into the argument. They have no real interest into looking deeply at questions or reality; they laugh at those that do.
Is this a problem to my answer? It just seems like another explanation.
Frankly, it doesn't matter if religious beliefs are truly held or not, the results are the same.
Trump supporters are fucking morons, I'd take 50/50 odds on there being a trump cult in the next 15 years that worship him as a second coming, and that would be valid as a religion.
questions that we don’t have scientific answers for yet, or that science can’t possibly answer
I'll be the Devil's advocate for this one and say that there are very few questions that science can't legitimately answer to any degree, like what consciousness is. But for others like why the universe became what it is today and how it works, it's just not a satisfying answer for someone who has no interest or hasn't studied physics and chemistry to a reasonable degree. Like, the way that we can partly explain a lot of what goes on from the flow of energy or that life's purpose is to reproduce in biology, what a let down of an answer that is for someone who was promised a grandiose explanation of everything.
Anyway, what I'm trying to say is that I can see why people retreat back to religion for these answers. And tangentially, this is why I think we need more people like Carl Sagan who can genuinely paint our understanding of the natural world in a more awe-inspiring way for the average person without becoming a meme themselves like some of these other celebrities.
Science can't answer any "why." It can explain how and what, but it can't give meaning. If someone thinks it does give meaning, they have turned it into a religion.