These risks could prevent Airbnb stock from delivering long-term returns to investors.Airbnb (ABNB -1.32%) has been one of the great post-pandemic winners in travel. With its global brand, durable free cash flow, and ambitions to build an "everything app," it's easy to see why the stock has drawn investors' interest.But no growth story comes without risks. For Airbnb, three stand out as the most pressing for investors: tightening regulation, margin pressure from new initiatives, and a valuation that leaves ...