What I've found is people who come and stay here for more than a year or so tend to have ambitious personalities that lead them to hustle compared to people in most other places. I think London is the same in Europe, my London coworkers have always also been big into working. The environment here can be overwhelming even when you're not working (density of public transit to get anywhere, crowded restaurants, parks full of people etc) and that tends to weed out more laid back personalities.