> You expect if you built a greenhouse or power generation source for indoor gardening that some government would spend the effort to send in troops or bomb you?
Well, if you are a US citizen, it is illegal to do that in Antarctica without a permit from the NSF (under the Antarctic Conservation Act). If you do it anyway, expect to be prosecuted, and the US will send agents to arrest you, even if you are in Antarctica. The FBI has made an arrest in Antarctica before (due to a fight at McMurdo Station).
All state parties to the Antarctic Treaty have similar laws, which (generally speaking) apply to their nationals worldwide.
If you were a sole citizen of a country which is not a party to the Antarctic Treaty – such as, Andorra or Afghanistan or Costa Rica or Cyprus or Ireland or Malta or Nigeria or Uzbekistan – then you'd have somewhat more chance of getting away with it. But surely your act would cause an international incident and they'd look at ways of shutting you down – the country of which you are citizen might suddenly decide to sign the Treaty as well, and shut you down. If the country of citizenship lacks the resources to shut you down, it may give permission to another country which does have those resources (e.g the US) to act against you on its behalf.