Listen to a Tesla biography - he very clearly had the premise and workability of tech that, in the wrong hands, could be used as basis for DEWs.
He was quoted as saying how he does not love humans, but loves humanity. He thought he was sent to develop the tech that would save humanity, and dedicated his life work to this goal.
He was known as The Wizard for his ability manipulate and understand the electric nature of the universe. Wayyyy ahead of his time. A perfect target for those wanting to corner the future into their own hands.