Found this awesome piece from the Millennial Money website. It's called 9 Best Side Hustle Ideas (2019).
It has plenty of interesting insights. Here's one that's particularly interesting:
The best and worst thing about side hustling is you can literally make money doing anything. You can often do them from the comfort of your own home.
It’s the best because you can find and make money doing something you love, and it’s the worst, because most people think there are no rules to side hustling, so they end up making some money on the side ...