Is it worth just investing all my GP into leveling 1 skill or no?

I have about 25M in my bank, and was hoping that if I do dump my currency into power leveling one skill that it would be able to make me a steady flow of GP either while leveling or after.

My main goal is quest cape, but I like to have money for supplies and gear upgrades so I'm trying to get a nice cash flow before pushing into mid and late game content.

https://imgur.com/a/sP5FBbL