If you are not a winning poker player (in other words, your long term EV at the table is negative), you're just going to lose money on average, so playing more means losing more. It only makes sense to play in that case if you actually enjoy playing the game and treat your losses as the cost of entertainment.
But if you are a winning poker player, you still won't win enough to rely on the income unless you are playing A LOT. And by a lot I mean every day, for hours a day. And even more if you play online because the level of play is so much stronger online than live.
And then, even if you are a winning player, and you play a lot, AND you have enough average cash flow to make it worth it, you are still going to have periods where variance wipes you out and you're down for months straight. It's pretty brutal.
After all this time, I decided I'd rather get a different hobby than spending so much of my time grinding away in a smoky casino. I just play (infrequent) home games now.