Don't mistake passive income with zero work. It's still work, it's just that your income is not directly tied to the hours worked. Anyone who owns rental properties knows that it's considered passive income but there is quite a bit of work involved. The work is front heavy but if you are lucky, you can collect rental checks without incident for many months before having to do work.
Ethiopia’s economy experienced strong, broad-based growth averaging 10.3% a year from 2006/07to 2016/17, compared to a regional average of 5.4%. Ethiopia’s gross domestic product (GDP) is estimated to have rebounded to 10.9% in FY2017. Agriculture, construction and services accounted for most of the growth, with modest manufacturing growth. Private consumption and public investment explain demand-side growth, the latter assuming an increasingly important role.
Peer-to-peer lending ($1,440 a year): I've lost interest in P2P lending since returns started coming down. You would think that returns would start going up with a rise in interest rates, but I'm not really seeing this yet. Prosper missed its window for an initial public offering in 2015-16, and LendingClub is just chugging along. I hate it when people default on their debt obligations, which is why I haven't invested large sums of money in P2P. That said, I'm still earning a respectable 7% a year in P2P, which is much better than the stock market is doing so far in 2018!

One of the things I'm surprised your article doesn't mention is the tax advantages of this type of investment. The depreciation and rehab costs (purchasing distressed properties) can be huge deductions to ones income taxes, which none of the others have. Then, along with the appreciation of real estate, this passive income investment outperforms the notion of maxing out my 401k as well.
These days, low-risk bond yields aren’t enough to meet most income needs. When investing in bonds, the income typically comes as coupon payments – contractually guaranteed interest payments at predictable intervals.  There are many kinds of bond income available, so you must strike a balance between reaching for higher income (yield) and limiting risk.