A saxophone (invented by mr Adophe Sax ) was a rather expensive instrument and had improvements from let's say 1850 until 1870. It was only used in the army. After the French-German war, it got somewhat forgotten. About 1900's, the saxophone was populair amongst some American clubs. In Europe musicians were supposed to play multiple instruments for a rather 'classical repertoire'. The leading class was fairly traditional and not very prone to accept new ideas and very opposed to changes. With all their privileges blown away after WWI, clubbing became more popular for them (they needn't hire an orchestra, could wine and dine in fancy restaurants instead of hosting themselves, etc... And all eyes began to turn to the USA way of living. So they adopted that lifestyle, and jazz was part of that. That's in a nutshell what happened.