Whether I carry the piano into my adult life doesn't matter. I've still learned how to stick through something difficult without quitting and moving on to the next exciting thing. The most valuable lesson learned in this story is that everything worth doing is boring and difficult sometimes. If you never stick through it beyond that point, you'll never learn that lesson.
You can be the most dedicated piano player, but if you later decides to channel that dedication into e.g. writing you are very likely to be struggling anyways. So now you are essentially in the same boat as everyone else.
Young people are mainly struggling because education, housing and long term careers are competitive and costly. Of course dedication can help with being successful in almost any sense of the word. But overall it is very likely overshadowed by other factors as e.g. your position in the housing market.
How many people who could afford a mortgage in a major city in their early twenties, by any means, are struggling with their lives today? Certainly a few, but surely a lot less than those who don't yet have a stable home in their thirties.
I'm arguing that it's not what skill you learn, but rather that you did. You moved past something being new and exciting, got to the point where it was frustrating and boring, and you kept going anyway. I'm now wishing I hadn't use a computer as my example because I still feel like you're taking the wrong lesson from my anecdote. I don't credit my childhood computer use for my successful career as an adult. I credit my (forced) single-minded focus, where giving up was not an option.
In this story, my siblings-in-law never knew that it gets easier, never knew that there is a plateau you can overcome, and never made it to the other side. Because they never had to. It's a story about not giving up, not a story about how everyone should learn to use a computer.
So I'm not sure that sort of life is an inherent quality of growing up with a computer. It's perfectly possible to push through the hard parts and find a passion with music.
You taught yourself to use a computer, without taking an expensive "kids learn computers class", right?
Signing kids up for all these classes and structured activities can lead to a sort of passivity where they expect adults to tell them what to do.
My early family life resembled the parent's. The difference in my case and related to your point wasn't the absence of distractions it was to get at them I had to learn how to make the damn computer work. I once tricked my 286 into thinking it was a 386 so that I could install Windows 3.1. All for the purpose of... playing solitaire. Yeah, that's how bored I was.
I'm not even sure I could replicate doing that today. As a 9 year old I was better with a rudimentary BIOS than I am today with a modern one. I'm pretty sure it was because there was a barrier between me and what I wanted and the only way to get it was to figure out that horrendous system.
Anecdotes, is all.
My wife's family wasn't rich, but the parenting attitude was "whatever you want, follow your heart". The kids had painting, sculpting, pianos, guitars, drums, dance lessons, soccer, karate, foreign language tutors, and anything else they desired. As soon as they got bored or frustrated, they quit and moved on to the next thing. The hope from the parents was if they were exposed to enough stuff, they'd find their passion. Of the three kids, only my wife has a steady job, and only because I nearly broke up with her when she was job hopping while we were dating. The other siblings quit their jobs at the first sign of any real struggle and move back in with their parents. I believe it's because they've never been forced to work past the uninteresting or difficult parts of any hobby or job in the past.
I don't know where the line should be drawn between giving kids every opportunity to find their passion versus making them stick with something they may not actually enjoy. I hope I figure that out before I have kids.