On the show I watched about robots on the History channel, they had one of the writers from a few of the Terminator movies on talking about his concerns and the parallels between what they’re doing now and the movies.
I think what it comes down to is the scientists feel driven to create, whatever the outcome may be. They hope it can somehow be used for good, and that thing that drove them to be scientists is driving them to create whatever they can. And then there’s the funding they get from sources that very much want projects like this to proceed.