Well, an argument could be made about using inherent natural resource wealth to fund X,Y, or Z as a free lunch. That is basically how Alaska runs its government with a net outflow of funds to its citizens each year, right? Of course, it's a highly volatile free lunch that could always be worth 3X or 1/3rd as much next year.
There's always an opportunity cost somewhere. What's to say funding X is better for the economy or society or whatever than funding Y or saving the money for a rainy day or giving the money to the people? What's to say natural resource wealth wouldn't be better managed by selling it to a private entity outright, who will try to maximize profit (the government has less of a reason to do that)?
So no, there's no such thing as a free lunch, even in your hypothetical.
Here, one can ask, for example, whether it is fair for non-college graduates who add to overall economic wealth - say your proverbial plumber - to subsidize college students taking classes in an economically worthless major, like most of the social sciences. Is society better off if the plumber had the tax money devoted to this to invest in his business? And we can ask whether overall tuition will go up for the so-called rich who aren't eligible for this "free" tuition. Or non-tuition "fees" like room and board or activity fees will rise as a result. Or if SUNY and CUNY schools won't be able to attract the best professors because there is less money to pay them. And on and on and on.
