100% agree on the opportunity cost. I taught myself Sanskrit to the level that I now teach two batches of students at different proficiency levels. I really wanted to learn it and I did it. I spent a lot of time to get to this level. Now I am learning to play guitar. I am finding it even more difficult than learning Sanskrit and everyday I find myself questioning the opportunity cost. Do I really want to play guitar that bad that I spend 1-2 hours every day practicing after coming home from my full time job? Instead of that if I practiced 1-2 hours of Leetcode everyday I could get a significant pay raise. Am I crazy to be spending time on something that is almost guaranteed to have a negative ROI - I ask myself everyday.