He Received His Pay

Did you know that some lawmakers refused their pay during the government shutdown?  I say that's a noble thing to do.  But Obama didn’t, he elected to continue to receive his pay, which works out to about $7,600 per week.  This is actually only a small fraction of the income Obama typically receives. He also collects another income stream from a completely private source as well. It’s averaged him more than $16,000 per week over the past four years. He’ll likely never elect to stop receiving this pay either.
What is this private source exactly? And what has enabled him to collect all this cash?  It's probably his investments.......to mention the possible source........