I feel like this problem wouldn't be limited to a person's use of the internet but would be an indicator of a person's lack of curiosity in general. The internet, at its most fundamental level, is just information. Saying you don't know how to "waste time" on the internet is like saying nothing interests you anymore.
The new internet has been carefully and intentionally designed to capture user attention and direct it into profit streams. Virtually all of the interactive online spaces on the web aren't trying to support community or educate minds or foster discussion, instead their sole purpose is to direct attention to those who will pay for it. The only notable exceptions to this are (1) open source software communities that ironically make the internet go and (2) the invisible private communities (various mailing lists, forums, irc) that use various technologies to hide from Facebook and Google and (3) the cryptocurrency communities (4) Wikipedia. (The last two communities are interestingly full of crazy poor people -- notably bad targets for advertisers). All the other spaces on the net have either succumbed to advertisers or been built from the ground up to serve the will of advertisers.
This is what has changed on the internet, not so much the information -- it's still mostly porn and cat pictures -- but the medium, the way that information is produced, managed and distributed. The question is to understand those design choices that allow online spaces to resist the advertising onslaught. The other question is whether people still want online spaces that do not serve the goal of advertising.