At least Biosphere 2 critically examined the possibility of building a self-contained ecosystem in a bubble on the surface of the Earth (a scenario so many assume would be no problemo). As the atmosphere inside the bubble got more and more awful, the zeal of the true believers declined markedly, until there wound up being nothing left of it but lame marketing, like the ironic fun of watching the worst movie ever made. Everybody wound up absolutely hating everybody else.
And that’s only on the macro-biological end. The really tough nut to crack was getting any experimental cooperation from the bacteria in the bubble. Humans turn out to be spectacularly inept masters of the biological universe, even a tiny test-universe.