"By developing “start-up skills” for four years, you are missing an opportunity to hone your skills as a writer, musician, engineer, architect, or whatever that secret aspiration was that you had before you decided it was necessary to make a lot of money first. It will be a regret that will not go away."
I did fully commit myself to build a company which gives me immense financial freedom and I definitely did not pursue some interests I wanted to. However, I have absolutely no regrets. Given a choice all over again, I'd choose building the startup without even thinking for a micro-second compared to wanting to pursue a career in music. Interestingly, now I can take private lessons on playing the piano when and where I feel like.
Money is definitely not everything and cannot singularly make you happy, but in today's world it's definitely the first thing you'd like to acquire to simplify getting most of the other things you want.