>> the tippy tippy top are down including gates and buffett. we've got $2.34 trillion among the 400 richest people in america. >> how do you find out what they're worth? >> we have a whole team that spends all year digging and digging. we talked to most people on the list. >> do they lie? >> there's a lot of lies. half of them lie higher, half lie lower. half want to be off the list and half want to be number one. a few of them are shooting straight with us. our numbers, we've got the best team out there and they spend all year just doing this. how much are these folks worth? >> any surprises? the youth. mark zuckerberg is worth more than $40 billion now. evan spiegel from snapchat, worth over $3 billion. he's only 25 years old. self-made. we have elizabeth holmes,