I will try to put this based on my little understanding of investments and how funds is being earned via several means and at the same time link it to various form of tax within my jurisdiction.

Anything you do to earn money, you're to declare your income because every options you listed there can be likened to social media advertising or say digital advertising which is done on a large scale that some people also establish a company for and they are required to pay their tax on such income derived. However, as an individual, you pay a tax different from what a company would pay. In declaring, you can go the route of either self assessment or wait for government to come after you  depending on your country residence.