And that target's a lot less than $10B; most of the BFR engineering is not about Mars but about a fully-reusable launcher, which is useful for launching anything, not just going to Mars.Sorry, I read your comment to read that you thought the cost would be much less (as little as their target of $10B), since they had already developed the launch vehicle.
If your point was just that if they can't do it for $10B, they won't, that may be valid but it's not the issue under discussion. We're talking about how likely it is that SpaceX will go to Mars, not whether SpaceX continues as a going concern.