According to 2011 census data, India has about 330 million houses and 247 million households. The household size in India has dropped in recent years, the 2011 census reporting 50% of households have four or fewer members, with an average 4.8 members per household including surviving grandparents.[331][332] These households produced a GDP of about $1.7 trillion.[333] Consumption patterns note: approximately 67% of households use firewood, crop residue or cow-dung cakes for cooking purposes; 53% do not have sanitation or drainage facilities on premises; 83% have water supply within their premises or 100 metres (330 ft) from their house in urban areas and 500 metres (1,600 ft) from the house in rural areas; 67% of the households have access to electricity; 63% of households have landline or mobile telephone service; 43% have a television; 26% have either a two- or four-wheel motor vehicle. Compared to 2001, these income and consumption trends represent moderate to significant improvements.[331] One report in 2010 claimed that high-income households outnumber low-income households.[334]
Building a smartphone or tablet app requires a fair amount of technical expertise, but it can pay off handsomely if successful. It doesn't have to be particularly complex or chock-full of features either; a simple one that solves a problem or is entertaining enough to attract users works fine. You never know what may suddenly become popular. For example, the minimalist game Flappy Bird was such a craze that at one point its developer was earning $50,000 dollars a day through in-app advertising. Of course, expecting a success like that is foolhardy, but one can always hope.
Some good writing here! I am a realtor myself and frequently get in touch with clients that consider buying a realty estate a conservative of investing. I once heard of a transport company in Vienna, Austria, which focused their entire profit on buying eventually every house available in the downtown for about 80 years. That must be some of a passive income!
I enjoy how you lay out real numbers. A lot of people wouldn’t do that. While you admit that you are somewhat conservative, I think the $1M in CD’s is just too conservative. Assuming you don’t need the cash flow now (which you say you just save anyways) then all that could be invested for potentially higher returns. For example, what if you bought San Francisco real estate along the way instead of CD’s. Or, an SP500 Index fund. I bet your average return would have been higher than 3.75%. Sure you could lose it, but the point is if you don’t need the cash flow now, you should try to increase that nut as high as possible until the day you actually need it. Your nut could be $5M right now if you had invested in asset classes other than CD’s for the last 14 years. Don’t get me wrong, you have done far better than me, but I guess I would take a little more risk if you don’t rely on that cash flow.
Indian Railways is the fourth-largest rail network in the world, with a track length of 114,500 kilometres (71,100 mi) and 7,172 stations. This government-owned-and-operated railway network carried an average of 23 million passengers a day, and over a billion tonnes of freight in 2013.[238] India has a coastline of 7,500 kilometres (4,700 mi) with 13 major ports and 60 operational non-major ports, which together handle 95% of the country's external trade by volume and 70% by value (most of the remainder handled by air).[239] Nhava Sheva, Mumbai is the largest public port, while Mundra is the largest private sea port.[240] The airport infrastructure of India includes 125 airports,[241] of which 66 airports are licensed to handle both passengers and cargo.[242]

For a person working for a wage, their source of income is their job, or their labor (aka their time that they sell to someone). But you can own a house, and rent it out, and when your renters pay you renter every month, the source of that income check is your rental property, or your house. It would just be called rental income. If you have money in the bank in an account that pays interest, those interest payments are another source of income. We can say the source is interest payments, or we can identify the asset that is generating rent, and say your money in the bank that is generating “rent” (aka interest) is your source of income.