Rainwater arrives on location, cost-free, and pure && You can turn poop into valuable manure through composting :: 0 fuel costs, 0 waste, 0 overly complex machines with 0 "exciting business models".
Your approach is fine for a rural compound, but doesn't scale for urban environments.
Perhaps these pieces of wisdom could offer some guide:
"When it rains it pours"
"Get it while the gettin' is good."
"Waste not, want not."
To me, rainwater capture can apply anywhere with a roof, a sky, and a mind to build cisterns.
As that fitting expression goes, "when it rains it pours".
As another fitting expression goes, "get it while the gettin' is good."
And yet another piece of wisdom, "waste not, want not."