Why would Google Amazon enter a market with 1 massive competitor losing billions subsidizing its rides? Why wouldn't they develop their own self-driving techno

Why would Google Amazon enter a market with 1 massive competitor losing billions subsidizing its rides? Why wouldn't they develop their own self-driving technology while at the same time assisting in the building of using ride sharing as a habit, and simply wait until uber goes out of business or retreats even further into "profitable" markets before unleashing their low cost self-driving fleet into those markets previously dominated by a heavily subsidized uber? oh wait a minute ...