The big thing about the DOW hitting 10k is that it's a psychological hurdle. More people will start to see it as an encouraging sign that the economy is improving and that it's time for them to get back into the investing game -- Never mind that the DOW's high water mark was 11.5k.
Many people are run by emotion, not logic. Companies financials may be turning to solid $ reporting, but the momentum of a climbing DOW is what's going to trigger them.
Just my