Most of the resources on Earth are practically unlimited even if limited in theory. Humans only ever tried to extract oil and minerals from the outermost 1% of Earth's crust, why? Not because they couldn't. They are already providing the right supply for the current demand. If demand increases, they'll dig deeper.

The concept of marginal utility which was mentioned here before is also important. "Unlimited demand" in your terms is not true, it's an ever-decreasing demand as one's needs get filled.