A couple more things to consider. It is HIGHLY unlikely that he will pay on the equity loan all the way to maturity. Odds are he'll sell that house and pay it off long before then.

Also, the interest is tax deductable and right now pretty darn low. (3.99% is available depending on FICO scores and debt/income ratio)

So in essence, he won't be paying $300,000 for $50,000 worth of toys.

Here's another old saying that I just made up: "If you can... then why the hell not!"