In this case, dangerous literally equals useful. Anything capable of working with vast amounts of energy is dangerous by the very virtue of humans being very fragile. Whether something is dangerous or useful is a function of how we handle/apply it.

But, generally, that's what we do. With brains, we can do in a few months what would take natural selection millions of years to "discover". Doing that, using our brains, seems kind of like the whole point of being a human.