> This article has nothing to do with wealthy families losing their wealth after two generations. The 70% number is a complete fabrication, they couldn't even be bothered with coming up with a more believable number like 73%, or even defining what amount is losing it.

The 70% is said to be an estimate. Now it's true that they don't get into detail about the estimate (and that's a red flag for this kind of article - I'd prefer to hear more details - the article's pretty light on substance as it is), but just to explain: it's considered bad form to give more precision in an estimate than is meaningful. People might be mislead if they said 73.25345% of families for instance, as it gives an undue semblance of certainty and accuracy (even if that's the number that your method of estimation came up with, you'd be better off zeroing the part of the number that's just noise). Giving a round number is considered more honest and a better communication of the uncertainties involved. Though if you're not familiar with these conventions it might seem odd.