Whether or not gay marriage and casinos on reserves are net positives for society is not the point. The point is that those people got what they wanted.
Potheads did not make any headway. Pot is getting legalized because the government can no longer afford to prosecute and incarcerate everyone who buys and sells it. When millions of Canadians start buying and selling guns on the black market without bothering with PALs and registration, perhaps gun control will go away on its own. Until then, you need a better strategy.