Billy has been the butt of criticism from friends for taking part in Hong Kong¡¯s protests. Undeterred, he sees his marching days as just beginning.

¡°We have to continue to protest until our demands are met,¡± said the 28-year-old accountant, whom Bloomberg chose not to identify. ¡°There is no end in sight.¡±

That sense of a long road ahead is one of the parallels between Hong Kong¡¯s mass rallies and France¡¯s Yellow Vests movement. Both are hard to pin down, determined and prone to evolve ¡ª a recipe for all sorts of trouble for their governments.