Millennials may be portrayed as frivolous spenders, squandering their cash on overpriced coffees and online barre classes in the face of pitiful long-term finances – but they are on course to become the richest generation in history , a study suggests. Those born between 1981 and 2000 are in line for a “seismic” windfall over the next 20 years, according to research by the estate agent Knight Frank, thanks to property assets accumulated by previous generations