You could, but your wealth today has already been set. You would not be richer than before you went back to the past in order to alter the present (which then was in the future).
But, you could travel to the *future* and buy a copy of the Wall Street Journal, travel back to the present and invest wisely. Since you travelled to the future and now know with certainty what will happen, quantum mechanics says that the future, now, cannot be altered. Just make sure you do not meet yourself, else your future will also be already determined.
Now where's that Tylenol.
"Since you travelled to the future and now know with certainty what will happen, quantum mechanics says that the future, now, cannot be altered."
Careful, the quantum cyber-harpies might swoop down and call you a Luddite idion, LOL. Or would that be a neo-Luddite?