Yeah, I've had this theory for awhile. The Swan sat on a micro black hole that existed in equilibrium within the Island due to its weird properties. Dharma, in its finite wisdom, decided to poke a hole in the dam so to speak, hoping harness the energy from a pinpoint hole in the black hole. This is why if you don't push the button it will destroy the world; it periodically vents the released energy harmlessly. If you don't push the button, the black hole escapes its captivity and devours the planet. The fail safe key permanently seals the Dharma hole in the barrier, so that no more energy can escape, but this also means Dharma could never hope to harness that energy for good (hence why they didn't just seal it in the first place).