If sociopathy is a mental disease why is it looked down upon so much? As if the person has a choice?

I was inspired by a question I read earlier. This person asked how they could exploit and manipulate the weaknesses of a clinical sociopath. This had me thinking for a while about how society views people with mental illnesses. It's not like the person wants to be ill, they cannot help it. These people should be treated or at least medicated not scorned by society. Why is violence and intolerance against people who suffer from mental illness so easily tolerated?