Actually you can't ever learn to play a violin properly unless you have an ear for music. There is a threshold of minimal talent that you can't jump over just by practicing, you either can hear it or not. While there is no such obvious threshold for e.g. math or programming (for a person with an average IQ), I think we could talk about a kind of a threshold defined by the concentration and willingness to invest time and effort into the learning process. Theoretically anyone should be able to do it, but in reality not everyone is mentally capable of that, simple as that. Just like running a marathon or something, most of us will never be able to do it, although in theory it's simple: you just need to follow the proper training for long enough. Losing weight is also dead simple, just as quitting smoking or getting off drugs, but many can't do it. Learning is no different, it takes certain minimal level of power of will to be able to make it.
Most people could run in marathons successfully, unless they are sick or something. It's what the human body was built for. And if you are going to argue that playing the violin requires an ear for music, as if that's so uncommon, then I could also argue that programming skill depends highly of intelligence.
> Losing weight is also dead simple
No it isn't, because weight gain and loss highly depends on one's metabolism. Say that to a diabetic and you'll probably get punched.
> Losing weight is also dead simple, just as quitting smoking or getting off drugs, but many can't do it. Learning is no different, it takes certain minimal level of power of will to be able to make it.
You say that losing weight is dead simple, and that you need minimal level of will power to achieve it, but then you say that many people can't achieve it.
