Somebody did a very scientific analysis of Jeff Bezos' laugh over time as he's gotten progressively more rich. And by scientific I mean they just spliced together clips of him laughing. Has it changed? Definitely. Is it more evil? Only if you think cartoonishly evil laughing is evil. The cadence of the laugh itself seems the same, it's just gotten deeper. Although it might just be all the children's blood he's been pumping into himself to achieve his goal of immortality.