warn

To alert somebody means to warn them about a potential danger.

If you alert someone, you warn them of potential danger.

Cipolla warned that the damaging potential of the stupid person therefore depends on the amount of stupidity inherited, as well as their position of power in a society.

And that's something that I warn all my baristas of.

A public health official in the UK warns that the drugs alone are not the solution, and that people should be encouraged to have a healthier lifestyle.

At a news conference today, a Foreign Ministry spokesperson said such economic warfare can only exacerbate tensions and warned that China will -- quote -- "take all necessary measures" to protect its interests.

The stupid person is the most dangerous type of person, and in groups far more powerful than the Mafia, the Military or Communism, Cipolla warned.