More Americans are using the internet now than 10 years ago, and there are more news websites and sites claiming to be news websites. Therefore, people are getting their information from a wider variety of sources, and more and more of those sources consist of fake news and conspiracy theories. The sheer number of conspiracy theories and fake news stories out there means that more Americans believe in them.
Conspiracy theories have been around for centuries. They are a way of explaining things that might not make sense otherwise, or they offer an alternate explanation for something we can't or won't believe. For example, some people believe a conspiracy theory that says the CIA killed Jack Kennedy. Because of the reach of the internet, and the speed with which information can be shared, when something happens in the world, a "theory" as to the reason appears almost instantly. Also, because of the scope of the internet, more and more theories are spread faster and faster today than they were 10 years ago. And, more people are likely to believe them.
The proliferation of social media, as well as the creation of websites by everyday people, means that conspiracy theories can spread at a much faster rate than in the past. The nation also has an educational system that is failing students and society alike, which means that America has an ever-growing number of people that lack basic thinking skills to discern between solid theories and baseless conspiracies. This being said, it is important not to interfere with the freedom to speak and publish diverse viewpoints. This means that the best solution to the problem is education.
Americans are not more likely to believe in conspiracy theories then they were 10 years ago. Yes, a certain segment of Americans do believe in conspiracy theories (always have and always will). However, the vast majority of Americans do not take conspiracy theories seriously. Some enjoy hearing about them just purely for entertainment purposes.