With the current rise of privatized space travel, one industry that may very well likely be popularized within our lifetimes is asteroid mining. However the initial investment cost of getting to a profitable asteroid will be enormous, the payoff of mining and bringing back the metals that these asteroids contain would be more than worth it. We are currently aware of 5 different asteroids that are worth multiple quintillion dollars at the current market rate of the metals that are contained.
However, to play devils advocate, the pure profit from these asteroids would likely be much lower if they were actually brought back to Earth, thanks to the laws of supply and demand. The price for the metals contained in these asteroids would plummet do to the massively increased supply.
Still, that does not mean it would not be fiscally worth it to go after these asteroids. It may be probable that industry would increase with the lowered price of these metals, allowing humanity to advance without resource limitation.
Source : Asteroid Mining
Johann's Astronomy Blog 