It's just perceived short-term self-interest. Their perception of risk is already skewed (all humans are like this), but has been skewed farther from reality with mass media programming and conditioning.

And then, stopping an addictive substance and controlling their appetite and urges takes real, personal work over an extended time period. Humans hate this. The shots are simple, fast, and require almost no work. Humans like this.

You just force an environment where your desired outcomes are the default path of least pain, least resistance, highest short-term reward.