Try and try until you succeed, goes the oft quoted aphorism. In Elon Musk and SpaceX's case, even if each attempt costs millions of dollars. After several disastrous attempts at landing, and even one disastrous take off, SpaceX has finally achieved the milestone that it has been working towards for years, possibly the very cornerstone of its existence. It has successfully, safely, and without incident, landed a Falcon 9 stage one rocket back to Earth. Almost ironically, it was more successful landing it on solid ground that it was in water-based attempts.