You would if you had friends and not a lot of time to waste.
Your reasoning is non-sequitur and based on assumptions. You're presuming that since I don't use facebook, that I don't have any friends, and therefore that is why I don't understand what there is to get addicted to. Gotta love the pattern "insult.... I'm not actually insulting you" of course not, your making hand-wavy generalizations about my social life without any basis in fact and asserting they are true. No, of course that's not insulting. It's like if I said "your Mother is fat. I'm not actually insulting you, my mother is fat too" or something.
First, let's go with your assumption that I don't have any friends. Why would "having friends" in that case reveal to me how it is addicting?
Again, I <had> an account. I had a number of friends, (both real and those that decided that since we both like a certain cereal we should be friends) and it was pointless. Aside from the fact that several of my friends weren't on facebook at all, For the most part when I wanted to contact them I didn't waste my time logging into facebook, I either phoned them, or more often, either e-mailed them or IM'd them. Thing is, I just didn't have time to maintain what was essentially excess baggage; I didn't have time to maintain and keep it up to date, so I had a facebookectemy and had the vestigial membership removed.
What I don't get is how, with Phones, cellphones, Instant messaging, E-mail, and so forth, people seem to think that facebook, and social networking in particular, is "revolutionary" and there is nothing like it. Social Networking is like a niche in an open field.