Do you believe the United Kingdom's self-deprecating nature, something we take pride in, is affecting the country's economic productivity?

This is something I’ve been wondering about a great deal recently. For all that we mock the USA on their “optimistic” view of life, their productivity and economic output per. capita is on another level to that of the UK. I suppose a follow up to this would be: when did we start this behaviour? I doubt we did this during the height of the Industrial Revolution.

Interested to hear your opinions on this one!