It is very possible to make a living playing online poker. I am one of the most honest poker players you will ever meet. If you are considering playing online poker for the first time, or considering getting serious about online poker, let me tell you this...
From someone who has been playing all types of poker for nearly 20 years, It cost me about 4k to learn how to play online poker. That's right, I lost about 4k before I started winning. Did I have days where I won $1500? Oh yeah, I had hours where I won that much, but overall it cost me 4k to learn how to play online poker. I stopped playing for about 3 months after dropping 4k online. I had to take a moment to reflect what I had done so differently than live play? The answer: Nothing. You have to play incredibly tight in order to make a living playing online poker. Also, you have to track your winnings every single day (whether you are a live player or an online player). I do that. Keep in mind, playing online, there will be times when you are running hot. You may make 3k in one day, you may also lose 3k in one day (both of those things have happened to me, & I don't consider myself that high of a stakes player, max I ever played online was $15/30). Max I ever played in NL was $5/10 NL. You must be patient though, patient & always play tight. In live games I am a much looser player than I am online. That is b/c it makes it much more difficult for people to read me (in live games). Online, there is no read, you either have it, or you don't. End of story.