I think smartphones are a bigger threat than PCs and laptops. People are less careful when they are on their phone. And they rarely use anti-virus or anti-malware software, ad blockers, etc., on the phone. Malicious links and spam spread through social media. The easy access to mobile apps is another potential problem. Most people download and install various apps and games without thinking about the consequences. There is now an app for almost everything you do online, and people use them rather than opening the browser and visiting the websites. The permissions you give these apps are worrying.