Earlier quoted context omitted.
Definitely not a waste of time. Learning to think in a non-CS way can be incredibly valuable. Will it make you a better programmer? Maybe not. Will it make you a more effective employee, founder, or person? Yes.
Why do you need to pay tens of thousands of dollars to for a second degree when you can just go to the source material yourself? Project Gutenberg exists, as does Youtube, Khan Academy, and many other free resources.
Also, when comparing what one would or wouldn't benefit from, I think money should be removed from the discussion. Obviously, you gotta live when you study and the longer you study, the less you're earning through work = time spent in school is a loss of income But as this is obvious, it's enough to focus on whether a double major is worth your time or not.