1) The median household income in Denver CO is $64,000. That's around 77% higher than in Altoona PA. Two locations specifically referenced in the article.
2) The opportunities that pay a lot more than that gap, do not exist to begin with in Altoona. Software, Internet, misc engineer jobs - the locations that people are fleeing from are death zones economically. Denver and Boulder are quasi boom cities; the Altoona's are the exact opposite; that means, over the next ten years your income will very likely expand nicely in those CO locations, whereas you're very unlikely to see meaningful improvement in Altoona.
3) Lifestyle is important for most people and likely that much more so for people willing to move across the country for better opportunities. Boulder and Denver are both incredible by comparison to Altoona PA, when it comes to lifestyle upgrade.
To answer your question, the people desperately fleeing from all those dying economic zones, seeking a vastly superior future, are extremely smart indeed.