Investors buying property to rent it out, are in effect speculating on real estate prices. By speculating, they are providing liquidity to the market and absorb

Investors buying property to rent it out, are in effect speculating on real estate prices. By speculating, they are providing liquidity to the market and absorbing risk from buyers, sellers, and developers. They make the market functional and contribute to price discovery. Having prices that accurately reflect the value of the asset will encourage developers to build the right amount of housing, so in a round about way, yes they do increase supply. The same applies to ticket scalpers. They absorb risk from ticket sellers, so there is less risk in putting on a show that might not sell all the seats, improving its profitability,