The United States and its partners continue to face a growing number of global threats and challenges. The CIA’s mission includes collecting and analyzing information about high priority national security issues such as international terrorism, the proliferation of weapons of mass destruction, cyber attacks, international organized crime and narcotics trafficking, regional conflicts, counterintelligence threats, and the effects of environmental and natural disasters.

If you are good at some subject, especially maths, science subjects, accounts or economics, you will have an upper hand in this business. There are plenty of such coaching centers so you will have to face some stiff competition in the beginning. But if you can get good results from your students, congratulations! You have made yourself a name and now parents will send their children in big groups to your center.

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.

I run several online businesses now (all it takes to start one is a domain, hosting, and maybe incorporation). There are two notable ones. The first is meal plan membership site called $5 Meal Plan that I co-founded with Erin Chase of $5 Dinners. The second is the umbrella of blogs I run, including this one and Scotch Addict. They pay me ordinary income as well as qualified distributions since I'm a partner.
Or, there is another theory for your primary salary – generate enough to have a little excess cash flow, but do it at a place that you can work stress free and have time to dabble in other projects.  A good friend of mine has this setup – he works 10-5 and makes $50,000 a year.  This allows him to easily cover all of his expenses, but the shorter hours and flexibility in his job allows him to pursue his secondary income generating ideas!
Consider refinancing your mortgage if you haven’t done so in a while before interest rates go up further. Or consider leveraging cheap money responsibly to acquire hard assets. LendingTree Mortgage has one of the largest lending networks online, and they will contact you immediately with their offers. You want lenders competing for your business, and get hard quotes so you can pit them against each other.

The one thing I learned though from all those childhood experiences though is that you never can depend on one source of income. Eventually my mom caught on and stopped giving me all those extra bags of chips and I had to figure out a new way to make money. No matter how safe something seems there’s always the chance that you could lose that income and be stuck with nothing.
DonebyForty Yes, that makes total sense! I hear you on the savings rate, too. I always figured I lived lean enough (and had enough saved up) that I could handle things even without my main source of income. However, after leaving my job last year and having a tough time with freelancing, I realized not having a job was more of a mental drain than a money one. I like knowing I have control and can call on another source of income and increase it when I need to. 

Capital growth in your portfolio can offset the eroding effect of inflation.  But any capital gains that exceed the overall inflationary effect can be drawn off to augment your portfolio income.  Of course, you must first generate those gains by making thoughtful investment selections.  While allowing strongly growing assets to keep doing that, it is prudent not to allow them to become a dangerously large part of your portfolio lest they go off the boil.  So if you selectively trim profitable positions along the way, you can boost your income.