I don't quite grok your example, as I don't feel piano is any easier than guitar. However, it's often far simpler to transition from a more rigorous pursuit to

I don't quite grok your example, as I don't feel piano is any easier than guitar. However, it's often far simpler to transition from a more rigorous pursuit to an 'easier' one. For this reason it could be logical to (e.g.) pursue an arduous, low-paying math PhD over a cushy tech job.