They expect to get ahead by taking shortcuts. And they can't bloody well handle it when others succeed.
In order to share the planet with difficult people, it often helps to try and guide them to more productive behaviour (easier said than done). In this case it would be helpful to let such a person think from a more abundant mindset, rather than through fear of loss (being a far more powerful and ultimately stifling emotion). Seeing the success of others can trigger fear of loss and lead to negative behaviour. Removing your mind from competition into creation will bring you above this fear-reaction cycle and lead to a far more balanced lifestyle, in my opinion.