Britain should have never gotten into it neither, so what if France fell to Germany, Germany still would have been no threat to the British Empire.
Well there was the thing about the Germans building a navy they didn’t need.
Actually, Germany could have guaranteed that Britain didn’t enter the war, but that would have meant no Schlieffen Plan. For Germany, the whole point of triggering the war was to prevent Russia from dominating Europe (which but for the United States they would have done). Attacking France was a rather strange way of accomplishing that.
But then in the next war Hitler justified invading the USSR as the best means of defeating Britain. The Germans haven’t had a sound sense of strategy since Wilhelm II sacked Bismarck.