It only takes a very few well-heeled (foreign) buyers at the margins to drive up an asset price. Classic cars are great examples; you get one or two bidders (1% - 2%) in a room of hundreds and you'll get $40,000 '73 Camaro Z28s, $100,000 '65 Corvettes, $150,000 air-cooled Porsche 911s ... and million-dollar crack shacks. 

Those who dismiss the impact of foreign RE buyers in this country are those who usually benefit from the inflation. Classic cars are an entirely different sort of asset (art), but the auction dynamic and impact of the marginal buyer is an established economic fact.