Sell an eBook.

Make a course or a program and sell it online.

YouTube ads revenue.

Affiliate Marketing.

Selling physical products online. (Shopify, Facebook marketplace, Instagram shop feature, …etc.)

Selling digital products online.

Ad revenue from ads running on your website.

Invest in stocks. (Index Fund).

Sell random stuff on eBay.

The average millionaire has at least seven streams of income.

Maintain multiple streams of income at all times.

Direct donations to Website, Patreon, Subscribe Star, Venmo, …etc.

Subscription, membership, or premium status. (Recurring payments for basic service with or without special benefits and perks).

Giving keynotes, speeches, seminars, or live events.

Direct support during live streaming through superchat on YouTube or other methods of donation because you showed up live somewhere.

Writing books and then selling them.