Airbnb is offering $750 to new hosts in World Cup cities, including Boston, who are expected to exceed the demand of over 380,000 soccer fans. The company will reward hosts who rent out an entire home in specific event zones during the tournament. The World Cup hosts could earn up to $210 million, according to a Deloitte study commissioned by Airbnb. The average earnings for each host will be $3,000. Boston hosts will be among the highest earning hosts, with an average earnings of $5,200.