My suggestion for making money in this space is not to build a CMS and sell it, but rather to build add-ons for existing systems. I use ExpressionEngine and I

My suggestion for making money in this space is not to build a CMS and sell it, but rather to build add-ons for existing systems. I use ExpressionEngine and I have seen popular add-ons sell for as much as the CMS itself (personal license.) That way you have left the hard part to the developers of the CMS (growing a community, attracting developers and building a customer base.)