what were the factors that led to a literary culture like Paris in the 1920s?

Recently rewatched Midnight in Paris (a guilty pleasure of mine) and it got me to thinking: Paris in the 1920s was such a miraculous hotbed of culture, from the Lost Generation writers, the Surrealists, the incredible cultural theorists, all concentrated in a single place. It would have been incredible to live through that time and in that atmosphere. But what was it exactly that led to this point? I'm sure there were economic factors -- some writers cited Paris as cheaper with a higher standard of living than many other countries. There is the rich cultural tradition of France. But is that it? Is there anything else that helped to create and foster this unique cultural moment?