string instruments are hard: you need to put the fingers of the left hand down in the exact right spot so that the note is in tune and the instrument rings out, and you need to learn how to bow so that it sounds good. to say nothing of articulation, vibrato, and all the other things that have to be internalized. it's not like this comes quickly, either. famously, it's very hard to make the violin sound good. it can take years, a lot of years, before it starts to sound good. a lot of people give up and never get there at all.
there's kind of an order in terms of how you learn a lot of this stuff when you take private lessons, and a lot of the pieces you learn might be solely to teach a particular technique, and you might work on that one piece for ages, until you're at a point where your teacher decides that, if you're not necessarily good, you're at least good enough, for now.
and in the face of this very heavily codified approach to music, learning a bunch of fiddle music on the sly feels a bit transgressive. oh, my bowing's not absolutely perfect? oh, none of this is in the western art music tradition?
part of the problem with learning the strings as an adult is that your brain is different from when you're a child. you learn things slower. your motor skills are more set, and you may have weird joint and tendon issues from, you know, not being six years old anymore. but there's also the problem of expectations: if you've spent much of your life listening to music, you form a expectation of how things should sound. listening to perlman or heifetz is incredible, but it wreaks havoc with learning to play the instrument yourself. you know how you could sound, in a perfect world. and you can hear the sound you're producing. if you're not tone deaf, on the bad days, it's hard to find the motivation to keep playing.
something about irish music breaks that for me. when i'm working through my quick daily practice (tenpenny bit, swallowtail jig, and others), i just...play. and if it sounds bad, i correct it. if it sounds good, i enjoy it, for however long it is until the bow grazes another string or i finger a note slightly flat. and this is the only time where, when everything clicks, the instrument actually feels right in my hands.
seven years ago we spent a few days in ireland, and our last full day was in bray, just south of dublin. and while the hotel we stayed in (the martello) was cramped and kind of run down in a charming sort of way, bray on the whole was a little unimpressive: after i climbed the bray head, there wasn't much else to do. we missed the fair by a few days. we went to the aquarium, and it was, as they say, a bit shit. but that night we found a pub by the water with live traditional music, and it was good. we sat there and had a few drinks and i don't think there was more than a dozen people in the pub. and watching them, i was caught up in it. and maybe it was the beer, but i thought, this sounds wonderful. maybe one day, i can do this too.