As interest rates have been going down over the past 30 years, bond prices have continued to go up. With the 10-year yield (risk free rate) at roughly 2.55%, and the Fed Funds rate at 1.5% (two more 0.25% hikes are expected in 2018), it’s hard to see interest rates declining much further. That said, long term interest rates can stay low for a long time. Just look at Japanese interest rates, which are negative (inflation is higher than nominal interest rate).
Scholarships, fellowships, and grants are sourced according to the residence of the payer. Those made by entities created or domiciled in the United States are generally treated as income from sources within the United States. However, refer to Activities Outside the United States, below. Those made by entities created or domiciled in a foreign country are treated as income from foreign sources.
The most liquid of the private investments are investing in equity or credit hedge funds, real estate funds, and private company funds. There will usually be 6 month – 3 year lockup periods. The least liquid of the private investments are when you invest directly into private companies yourself. You might not be able to get your money out for 5-10 years, depending on the success of the company and upcoming liquidity events.
Build a list in a particular niche and tell them stories. Create a bond. Build a relationship with them. It's important. Then, when you've created a bit of culture, start marketing affiliate products or services to them that you think they might like. Just be sure that you personally vet out whatever it is that you're selling to avoid complaints if the product or service falls short.
You can select any of the above-mentioned, based on your interest, skill, and capability to generate a second income source. However, these are just to name a few, there exist multiple ways to generate a secondary income channel. You just need to identify the right one, which suits you the best. Remember there is no shortcut to success and you need to work hard to be successful and rich in the long run!
An obvious example is over exposure to bank stocks, which have been excellent investments for over a century.  Though a foundation of most portfolios, bank stocks do involve more risk at certain stages of the economic cycle than many realise.  Being less exposed to bank shares in the last few months could have preserved some capital.  So, a more diversified approach can help mitigate some of these risks.