1. the Chineese government got their backs. (e.g. foreign competitors have been forced to agree to not sue these guys to get their mergers approved)
2. they make long term strategic decisions. xiaomi is owned by the employees and don't have any short-sighted shareholders to please
3. their engineering and manufacturing teams have a very efficient iterative workflow. many other companies ship a product and move on to the next but xiaomi updates and improves their products every four weeks (eight ?).