Consider the stock of ocean tuna which is massively overfished. it is rational for an individual to exploit the resource rather than to conserve the stock because

Ocean Tuna is massively overfished even though there is already an abundant supply. The reason for this is that it cost less to harvest the fish than it does to maintain a stock of the fish. This answer however, is still debated by some experts who argue that this method is not healthy for our oceans.