Focus on your primary passive income stream first. It's difficult to grow your passive income into multiple streams if you don't already have one, solid stream. Focus all of your efforts on that one project first and help it grow as productive as possible. Then, you can take the money you've made and lessons you've learned from this passive income stream and put them into others. 

I’m looking at accepting a professor job. It’ll be more than a 50% pay cut. But I’ll have the same life you describe – endless summers and an entire month every winter to ski. I’m thinking in the end, eventually, I might even end up wealthier in more ways than one. Happy people tend to be the most successful. I have no desire to diversify. Dividend stocks allude me. CDs seem like a good choice for older people, but I have time on my hands and real estate knowledge, so I’m sticking with what I know, despite the fact that most people will tell me it is foolish and I should diversify.

You are valuable. Your time, your work, knowledge, experience, and output are all valuable. In fact, your employer (or your customers, if you’re an entrepreneur), probably pay a lot of money to rent these things from you. The problem is, whether you’re a doctor, a lawyer, an artist, an engineer, or even a baker, the value you create is consumed once — then it’s gone. You can only sell a loaf of bread once. You can only sell each open heart surgery to one client. The value trades hands, and now it belongs to the customer — you get paid once.

I think you should use Financial Samurai to raise your passive income. You’ve already proven that you writing 3 articles a week is enough to not only sustain the site but grow it. Why not have more guest writers post articles? Since you started with the extra post each week I’m guessing traffic is above your normal growth rate. Leverage that up with more posts and my bet traffic will continue to grow.

Returns on real estate investing vary and you don’t want to get into the business based on an estimated return but on your own calculation of what is possible for your local market and for specific properties. I have seen pretty common averages between 8% and 12% a year for single-family residential rentals with cash flow accounting for between 0% and 6% of the return.
One of the great things about generating passive income via rental properties is the ability to buy properties throughout the country instead of just in your generally locality. Because you will hire others to manage, maintain, and repair the property, you don’t have to be in the same location and can maintain passive ownership from virtually anywhere. That gives you the ability to better choose rental markets where you stand the best chance of profiting the most due to lower local and state property and business taxes.
Creating passive income is the key to retiring, especially retiring early. If you want to retire early with the stock market you will have to save a huge amount of money, because that money has to last so long and retirement calculators depend on you using your investment to fund your life. With passive income you will have income coming in as long as you own the investment, without every eating away at the principle invested. Creating passive income may take more work than investing in the stock market, but I think it is well worth the extra effort!