An important aspect of why high-income people may behave this way is that the tax code incentivizes it, at least in the US.

Buying a home? We've got this nifty tax deduction for your mortgage insurance!

Funding your 401(k)? Cool! No tax on those contributions for you!

Say you make $250k a year, so your overall marginal tax bracket is 32%. Your annual mortgage interest is $44k, and you and your spouse each max out your 401(k) contributing $30k for you (being over 50) and $22.5k for your spouse.

Without these deductions and taking just the standard deduction, your taxes would be around $61k (ignoring things like capital gains rates, etc.).

However, if you max out your 401(k) plans and have that mortgage interest deduction, you save about $35k in taxes, paying less than half - about $26k.

That's better than getting a 20% raise!