What is bad have done by scientists?

What is bad have done by scientists?
Like people there are bad and good scientists. Probably one of the worst things done by scientists is developing nerve gas. Nerve gas has no other use than to kill people and nerve gas has been developed by scientists with the aim of making them as lethal as possible. I really don't know how they sleep at night but i presume they go home to their families and hug their children. Many other things are developed by scientists with the sole aim of killing people more efficiently and if i listed them here it could run to hundreds of pages. Most scientists work on making this world a better place to live in though.