Rofl Pwny/Kirin's Thoughts:
I bought World of Warcraft back in December 2005, not knowing what I was getting myself into. One of my friends had already been playing for a month or two and had a 30-something Paladin and convinced me to try the game. When I bought it we decided to start Horde characters on the server Bloodscalp.
He started an Undead Warlock, I started a Tauren Shaman. We leveled up for a while, then I decided to switch to Orc Warrior. It started rather innocently, playing on and off with each other, although since I had restarted with a new character he was levels above me. Before I knew it, however, the addiction set in. I was gaining multiple levels a day and was catching up to my friend's Warlock.
He was the first to reach 60, but I was not far behind. I then went through a few different guilds before I joined a PvP guild that I really liked. This is where it really became bad. This was a serious guild, and we PvPed all day, every day. This was during summer by this time, and I would be PvPing with my guild all day until often 4+ AM in the morning, then sleep in and start all over again in the morning.
This went on for a long time, until I started an Undead Rogue. I originally made him to be a character for farming, but quickly grew to love his playstyle. As Burning Crusade was setting in, I leveled him quickly all the way to 60 in time for the expansion, and continued leveling him all the way to 70 in Outland.
After 70, I went through a few guilds and raided Kara, etc. with them. All this time I noticed I had a problem. Grades in school were dropping and I was now hanging out with friends online in WoW instead of in real life (most of my friends also played WoW). Over time many friends started dropping from WoW until it came down to a core set of my friends who still played. Some of the others who had quit would often restart for short periods of time, still trying to break the addiction but not being fully able to do it. Eventually it got down to just one friend and I playing.
After a while, he got to be in a great guild (he was a 70 healing specced Druid, after all) while I was stuck filtering through lower guilds (**** overpopulation of Rogues), though I kept playing. Turns out though, he was the first to quit. He eventually realized it was taking over his life as well, and quit. To make sure he never played again, he sold his account for $400 on Ebay. ><
I kept playing for a bit, and while I still had most of my in-game friends, it degraded without my real life friends. I attempted to quit multiple times, until finally I forced myself to quit. I still have my inactive account, but after 1 1/2 years of playing I decided it was time to get my life back.
Even worse, even after quitting I still visited worldofwarcraft.com often. It's THAT hard to break. Thankfully, that stopped after a while too.
I am now WoW-free and glad.
/rant
Long story short, don't start. EVER.