And of course it's equally a cliche for Europeans to observe the US's wealth, long hours, short holidays, low taxes, extreme inequality, etc., and shake their heads, noting the ostensible causal link to various forms of societal dysfunction (see, e.g., http://moses.creighton.edu/jrs/2005/2005-11.pdf which is ostensibly about correlations between religion and societal health, but a lot of the clearest correlations are driven by the fact that the US is both very religious and badly messed-up).

Whether the US's unusually severe work habits have anything to do with this is anyone's guess. Quite likely they don't. If they do, they might be effect rather than cause. But I don't think the connection between those work habits and the US's great wealth is at all obvious, either.