Affiliate marketing Am I missing something?

Ok so I get Wordpress I get hosting I get the content for the website I buy an seo package to get traffic & I set up the landing pages on the website and of course collect the emails but saying it like this just sounds too easy can someone fill me in on what I’m missing? I don’t wanna do all of this and fall on my face

Even if you buy SEO, there is no guarantee that site will rank. In case, it ranks , all can go waste in future Google update. So it is not that much easy as it sounds.