As mentioned in the comments here, there are companies like MongoDB, Wordpress & Spring Framework (of which its parent company was sold for 420 million dollars)

As mentioned in the comments here, there are companies like MongoDB, Wordpress & Spring Framework (of which its parent company was sold for 420 million dollars) which have open source products at their core and have been successful companies financially. I would argue though, that many of these successful companies are more platform providers than SASS.