Men are cruel, but Man is kind?

Even within the same man. Experiments have been done at Stanford and Yale, and it was found that depending on the information provided to the individual, they can become demons. They had to stop the experiments, because they didn't know how far the individuals would go to harm others.

Usually, 'men' are individual humans and 'Man' (with a capital M) is humankind viewed collectively, thus individual men may be cruel but humankind as a whole is kind.

Thank you both