I like the way you have listed the ways to earn extra income and was quite surprise that you did not make mention of network marketing, which is a way to make extra income without quitting your regular, though most people view mlm as a pyramid scheme but the real pyramid scheme is a regular 9 to 5, because you can only have one president of a company at any given time and network marketing business model to promote product that can be used is really cheap to join and can offer a substantial extra income or what do you think?
While compiling this list, I did my best to avoid scams, and stick with practical ideas that work. I have tried many (but not all) of these ideas. Some of these helped me earned a few dollars here and there, but there are some that helped me earn extra money on the side every single day — and some are still providing me with revenue! Note that not all ideas will fit your skills and abilities. What works for you depends on your abilities and your current financial situation.

Portfolio income can come from multiple sources – interest/bond coupons, stock dividends, financial strategies including derivatives and capital growth.  Each offers some cash flow and some also offer potential capital gain with some risk from liquidity and volatile prices.  In this low-yield environment, many investors rely too heavily on cash flows and to pursue this are venturing further into riskier areas than they’d normally consider.