Why is marijuana constantly linked to failure?

I think a lot more people smoke marijuana than the statistical numbers that the government gives us. I mean, look at this whole situation with Micheal Phelps, it completely ruins the whole image of "if you smoke weed you will go nowhere in life" like those anti doping commercials such as above the influence. I know tons of successful people who smoke, the only difference is they keep it on the DL for fear of persecution from either others or the government. It's time for the laws to change, for the people sake.