$2.9 is probably conservative but whatever the "real" value is, the point is that it's nowhere near $10B. Even if you double the estimate, which is also probably unrealistic, you still have the issue of Trump overstating his net worth.
Does that really matter to anyone though? I doubt it. People support Trump because of his views, however fucked up those might be. He's willing to say what a big chunk of the conservative crowd thinks and believes and they like the idea of someone who is going to publicly say 'fuck you' to all of the political correctness.
I think right now we're only seeing the tip of the Trump iceberg. I'm sure he has a lot more non-PC views that he's not talking about but will if he feels he's got the support. IOW, it's just a matter of time before he becomes overly confident and his comments actually start to cost him support.
But that won't happen until he's polarized the other leading candidates. They're going to be forced to try to one-up Trump to get any attention at all. We've already seen that happen with Huckabee. That's going to continue until everyone is so far to the right that the boat capsizes, meaning until the Reps produce a candidate that has virtually no chance of being elected. The Dems could nominate Satan, or hell, even Hillary, and still win the election.