Seriously, there are lots of great careers for someone in your position to pursue, why go into something where the deck is completely stacked against you? Even if you do succeed it will take longer, and not be to the level of where you could have been in an another career track. Take it from someone who has been through that ringer, if you do go for a PhD it should only be because you have a plan for an immediate exit from academia when you finish it (i.e. you are just "getting your union card").
The fact that you are questioning tells me you might not truly want this, and the only, only time I would ever suggest someone follow this track is if they have an unbelievable burning desire for it. That's what it will take!
"I'm not afraid" you say? You will be.