They think working as an affiliate is easy because they only need to share the link. But it won't be that easy. They must be able to find the right place to promote their affiliate links. This is difficult because many people already use social media to spread their affiliate links. They must be able to compete with other people who may also use the site to promote.
Maybe you need to try a rotator site that will display advertisements for the site you are promoting for people to see. I've seen someone use it to promote multiple sites. But I don't know the results because I didn't pay much attention.
I agree with you, I have tried to enter the marketing affiliate world before and all I can say is that it is not as easy as what we see from other people, before you can make money here, you must first invest in the tools that you will use to affiliate and that includes hard work and advance knowledge about technology. Aside from that, you need to keep up with the trend in order to gain viewers, clients or consumers.