As long as there is still the written word, there will always be editors. Freelance editing and proofreading not only pays a decent hourly wage, it also gives you the chance to read about potentially interesting topics too. What's more, pursuing freelance writing & editing as a business idea can afford you a lifestyle that lets you travel the world as a digital nomad. You can find lots of job postings from companies and individuals in need of writing, proofreading, and editing services on Upwork, which makes this a high-demand opportunity to make money online.
One of the cool things about Google AdSense is that it's so easy to get set up. If you have a blog or website, you can sign up for a free Google AdSense Account. From there, Google will give you a unique code that you will paste onto your website. Google takes it from there, tracking your page views, traffic, and earnings on your behalf. There is no upkeep or maintenance to get this thing going, which makes it a no-brainer if you have a website already.