Ehh they could be borrowing against assets they currently have with their money management firms. Have $2mil in assets with Merril or whoever, get a $1.5mil “loan” against your assets in cash at a competitive rate and use that to purchase your home.It's another tax on the wealthy/middle class to subsidize the lower economic section of the income tax bracket so high risk mortgages can be better backstopped by the govt without burdening forecasted budgets.
You could undo the govt backing of jumbo loans north of $1m but I think you'd find not many would lend without at least 8-10% interest rates to offset the risk. That would tank the market, with knock on downward pressure on lumber, concrete, building materials, etc, which impact markets, labor/unemployment etc.
The wealthy aren't borrowing presently, 3 houses near me have sold for north of $1.8m, all were all cash deals. So the wealthy aren't borrowing and the middle/lower brackets won't get approved at current rates. Quite the conundrum.
Unless your point was they aren’t borrowing in the traditional sense, in which case ignore me