https://treaties.un.org/Pages/showDetails.aspx?objid=0800000...
Perhaps you're forgetting that the initial detailed resource assessment (exploratory drilling etc.) is also prohibited, which stops investment from getting a foothold.
(I spent a lot of time down there)
Edit: thinking a bit more... Why do you say the treaty isn't enforced? I've been under federal investigation for what some people thought was a violation of the Antarctic Conservation Act (US law enforcing the treaty). I don't think anyone has ever been charged under that law so you could be right, but I was scared and I assure you people take the ACA seriously.
But there certainly were substantial whaling stations in Antarctica for a while, with quite a lot of people & much more primitive technology compared to what we have now.
Do you know about the overlapping territorial wedge claims in Antarctica and how they were suspended by the treaty? If not I think you would find it quite interesting.
Given that there's laws and international treaties forbidding mining, resource extraction or resource exploration, of course it's not economically worthwhile.
Wikipedia gives the entire island's population as 144 - all of them at a military base. [Edit: Vs. a population of ~61 million for Great Britain.]
Actual daily life in the high arctic/antarctic is nowhere near so desirable as many people want to believe.
To save the possibility of finding life we are preventing ourselves from finding life.