"To be sucked in" does NOT mean to waste your time. In some cases it might, but not necessarily.
It means to be so interested in something, to be so captivated by something, that you generally lose sense of time and you focus solely on that one thing.
For example, you might watch a few YouTube videos and get "sucked in" and then two hours later, you're still watching YouTube videos. Or you might watch Lost on NetFlix, get sucked in and binge watch 5 or 6 episodes in a row.
It can be a negative thing, a time-waster, but it can also be a positive thing where you are highly focused.