Some more points about demerits of internet
Spamming, virus threat, pornography is the main demerits of Internet.
Like all the gifts of technology, internet has countless advantages. It gives us an easy access to knowledge within the four walls of our homes. But it also has several advantages. For instance there is improper stuff easily available on internet which can corrupt our children. It also weakens family ties, since people are spending more and more time online and very little time with their family. There is also a chance of being hacked online. You can never trust what people tell you about themselves online because there is no way you can verify the same. So it is good but in moderation and it's important not to trust people you know off the internet, blindly.
I think there is no demerits of internet