Various explanations have been proffered. Is it that I am talented? If so, why do talented people usually play only one instrument? What is talent anyway? We think it's innate or genetically endowed; the luck of the draw before we were even born. But the current research in psychology and the brain tells us that what we call talent is really just achievement, and that all achievement is just the result of hours of focused practice invested. Furthermore, early achievement can't predict future achievement. So "talent" is virtually meaningless.
A better explanation was hinted at by traditional Newfoundland ballad singer Anita Best. The people who perform traditional music are merely those who have had access to it, and who have been interested. Of course it helps to have patience and dedication to assure the refinement of the craft, but that is true for just about any human endeavour.
I propose a third factor: a personal experience of loss. It seems to me that many of the greatest proponents of traditional music have been immigrants or members of a minority. People from communities that are lost due to urbanization or resettlement tend to be fiercely proud of their heritage, and very eager to share their language, stories, and songs with others. These are things that they can hold on to no matter what.
I was fortunate that as a child I heard a lot of traditional music. My father was part of a musical group of British ex-patriots called The Friends of Fiddler's Green, and my sister and I were taken regularly to The Fiddler's Green Folk Club. Some of the children of other members of this band also have grown up to become musicians. But only my sister and I have specialized in traditional music. It could be that we just liked it more than the other kids. But our interest may have been strengthened by a sense of loss. My family moved away from the Toronto folk scene when I was ten, and my father died when I was sixteen.
I play folk music and folk instruments because I know that if I don't, very few other people will. I sing traditional ballads because they are beautiful and hardly anyone even knows anymore that they are beautiful, or how they can be presented to be fully appreciated.