How to Understand a Great Man's Actions
The legend is that Edison promised Tesla a huge bonus if he could get their electric generators to work above a certain high level of efficiency. Tesla managed to do it. When he demanded his bonus, Edison laughed and said, “Nicola, you have to learn to understand the American sense of humor,” and didn’t pay up.
So yeah, Edison wasn’t a great guy.
On the other hand, Tesla later claimed to have invented a death ray, so they both have their issues.