It is certainly easier to make friends when we are younger, because life allows it. Those years are filled with school, sports, extra curriculars. Those are the times when everyone and anyone can be a friend.
As we age, we weed out those who aren't aligned with our core values, interests, etc. In my experience, as we age, our circle of friends becomes smaller but more meaningful.
However, as a hospice volunteer, I've read lots of research on "regrets that dying people have" and one of the top regrets is not keeping in touch with friends/socializing more often.
After learning that, I am so much more aware of my relationships and time spent with loved ones. And I'm never afraid to make a new friend!