While it is possible to earn affiliate revenue without building your own website, owning your own site has many advantages.
When you build a website with your own domain name, you're creating not just a stream of revenue but you're also creating a valuable asset that you own and are in control of, and you have the option of selling one day.
When you create content, that content helping build up YOUR equity, not someone else's site.
Everything has risks, but when you own your own site, your business model depends much less on the latest fad and less on the whim of third-party tools, gadgets, companies and other people, all of which have the potential to disappear.
I own affiliate sites that have produced revenue month after month for more than a decade. Yep, it takes time to build a site and attract links, but all those keyword-rich pages and all those links to your site are like money in the bank, or like little slaves working tirelessly for you, 24 hours a day.
That's a pretty good investment, I reckon.