Writing and publishing an eBook has become a widely popular means of earning passive income in recent years. eBooks on non-fiction topics like online marketing, business development, career advice, and the like are especially successful. While fiction eBooks are also good sellers, the market for them is much more competitive as compared to non-fiction ones. Once you've written an eBook, you can put it up for sale on platforms like Amazon's Kindle Direct Publishing or Apple's iTunes Connect.
As a private lender, you can lend to anyone in your social circle. For example, many home rehabbers need access to a source of capital they can tap into very quickly in order to fund the initial purchase of their properties. You can partner with a rehabber who uses your capital for a short-term in exchange for an interest rate that is mutually agreed upon.

Another way to generate passive income is to invest and be a silent partner in a business. This is very risky, but with risk comes the potential for high returns. For example, several years ago both Lyft and Uber were looking for private investors to invest in their companies. Today, they are worth billions - but you as an investor would only reap that benefit if they go public via an IPO, or get acquired. So, it's risky.

What’s also really important to realize here is that when I took the exam I was teaching people to study for, I didn’t get a perfect score. In fact, I didn’t even get close to a perfect score. I passed. But I also knew a lot about this exam—way more than somebody who was just getting started diving into studying for it. And it was because of that, because I was just a few steps ahead of them, that they trusted me to help them with that information. To support this, I provided a lot of great free value to help them along the way. I engaged in conversations and interacted in comments sections and on forums. Most of all, I just really cared about those people, because I struggled big-time with that exam myself.
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.