Thousands of Airbnb hosts expecting a World Cup payday are still waiting for guests as a combination of high travel costs, steep ticket prices and restrictive border policies dampen demand . With the tournament set to begin in June , data from rental firm AirDNA shows that Boston is currently the only host city where more than half of the available inventory has been reserved, at approximately 55 percent, The Wall Street Journal reported. Other markets are trailing significantly. In Philadelphia, only 42 percent of rentals are occupied for the group stage, while several other cities reported even lower figures. The sluggish demand comes despite significant investments by homeowners. Mae Stewart, an Atlanta-based design consultant, told the WSJ that she spent $60,000 renovating her three-bedroom home specifically for the tournament. She is seeking $4,500 for a week-long stay in July — triple her usual rate — but her property remains unbooked.…