A Question for Millionaires

[Justin James]

There is endless information on how to get started in real estate and finance, but not many good resources on what to do once you've firmly rooted yourself in the middle-class. So, for any highly successful person that might be reading this, what resources did you use to scale up to the next level? Any book recommendations? 

I suspect there isn't much information on this because there are so few people to ask. Once you've mastered "Middle-class investing", where do you go from there?