While I believe that every child should have the opportunity to participate in musical activities, and I think that it is beneficial to everyone to study an instrument (or voice) with a good teacher, I have learned from experience that the only people who truly succeed at playing a musical instrument are the people who get enjoyment from the hard work of practicing.
Getting from can't to can is a profound journey, and it is a journey I have taken many times with different instruments. I have finally found the instrument I love to practice most of all (the viola), and feel extremely fortunate that I have put in enough work so that I use the word "can't" only rarely. I also love the journey between can't and can with the viola as much as I appreciate being able to play my instrument in a way that expresses my deepest inner voice. And every new piece allows for the possibility of a new and interesting journey.
In my nearly 40 years of teaching (nearly 40 years!), the students who seem to have gotten the greatest benefit from studying music are the students who enjoy the process of making improvements in their playing by taking baby steps: notching passages with a metronome, becoming aware of how they feel when using their playing mechanisms efficiently, and gaining an understanding of the possibilities to be found in a musical phrase.
Some people are "wired" to practice and play, and some people are "wired" to do other things. People who do not get pleasure out of the process of practicing might find that they get more pleasure out of the process of working hard at something other than music. My hope is that my students who no longer play find an area of concentration that asks them to work hard, and that they find joy in the process of improving in their area of concentration through consistent work. I also hope that they keep music in their lives and do not associate no longer playing with a sense of failure. And then there is the secret pie-in-the-sky hope that when they get to a point in their lives where they want to try playing again, I hope that they find new enjoyment in the hard work that all of us have to do in order to get from can't to can.