Learn makes earn ,we all know.It can be a principle,it is a principle.To make it in life there should be rules made by individuals and should followed too. Practice makes perfect, mate.I listed a few well known sites to earn knowledge for free.

Learn Equals Earn
•edX
•Alison
•Ted Ed
•YouTube
•Memrise
•Duolingo
•Skillshare
•FutureLearn
•CreativeLive
•The big know
•Digital Garage
•Academic Earth
•Stanford Online
•LinkedIn Learning
•General Assembly
•Harvard Extension
•Open Yale Courses
•MIT OpenCourseWare

Disclaimer:I'm not a financial advisor and this is just my personal analysis, it is not be construed as any kind of investment advice. Please conduct your own due diligence.