1. The batting cage idea is very risky. I’ve seen many of them close over the years and it is not anything close to passive income if you want to keep the business going. You have to continually promote it and target youth leagues, coaches, schools etc to catch all of the new players who grow up and want to play. I’ve played at probably 8 batting cages over the years and 7 of them closed.
One of the most appealing options, particularly for millennials, would be #12 on your list (create a Blog/Youtube channel). The videos can be about anything that interests you, from your daily makeup routine (with affiliate links to the products you use), recipes (what you eat each day) or as you mention, instructional videos (again with affiliate links to the products you use). Once you gain a large following and viewership, you can earn via Adsense on YouTube.
Instead of buying lots of individual bonds, you can buy a bond ETF to diversify among many bonds and leave the selection to the ETF managers. Bond ETFs come in many different varieties including government, corporate, short-term, long-term, junk, municipal, international and in variations and combinations of each type. Like most investments, higher yields mean higher risk. So choose your bond ETFs based on your risk tolerance, asset type, and liquidity.
For those willing to take on the task of managing a property, real estate can be a powerful semi-passive income stream due to the combination of rental and principal value appreciation. But to generate passive income from real estate, you either have to rent out a room in your house, rent out your entire house and rent elsewhere (seems counterproductive), or buy a rental property. It’s important to realize that owning your primary residence means you are neutral the real estate market. Renting means you are short the real estate market, and only after buying two or more properties are you actually long real estate.
5. Make sure you are properly diversified. Capital preservation is underrated. We saw a lost decade for tech stocks between 2000 and 2010 after the first dot-com bubble burst. It actually took 13 years for Nasdaq investors to get back to even. Investors in the Borsa Istanbul stock market index just gave up 10 years' worth of gains after they saw a plunge in their currency, partially due to increased tariffs by the US and a lack of confidence in the government. Your passive income needs to be properly diversified in order to take the hits.
Truebill is an app that helps you save money by identifying recurring subscriptions and other bills and helping you cut costs by negotiating better rates and fees. One of their partnerships is with Acradia Power, which has the potential to save you up to 30% on your electric bill. It searches for better power rates in areas where competition is allowed, and it locks in the better prices for you.
Residual income is the amount of net income generated in excess of the minimum rate of return. Residual income concepts have been used in a number of contexts, including as a measurement of internal corporate performance whereby a company's management team evaluates the return generated relative to the company's minimum required return. Alternatively, in personal finance, residual income is the level of income that an individual has after the deduction of all personal debts and expenses have been paid.