Writing a book is an incredibly challenging task, and one that can take years to complete. Once the book is written and published, it doesn’t take any effort to maintain – unless you revised it down the road due to a change in your field. The risk is that no one downloads or buys your book, but there is considerable upside if you manage to find a following. There are a number of places to publish books online these days like Amazon.
Real-estate crowdfunding ($9,600 a year): Once I sold my SF rental, it was natural to reinvest some of the proceeds into real-estate crowdfunding to keep sector exposure. I didn't invest a lot in some of my favorite real-estate investment trusts because I felt a rising interest-rate environment would be a stronger headwind for REITs. But if I could be more surgical with my real-estate investments by identifying specific investments in stronger employment-growth markets, I thought I could do better.