http://www.taxpolicycenter.org/model-estimates/individual-in...
For someone earning $500,000 a year, a $5,000 tax break is a $5,000 tax break, it isn't going to do much of anything to their behavior.
Considering that mortgages usually require a down payment, you could also make the argument that the benefit overwhelmingly accrues to the financially stable. People that can't get the down payment together aren't going to be stabilized by a benefit they can't access.