I’m sure no one needs us to rehash the “rent v. buy” debate in another thread, but you end up running some of this risk either way - because rents and prices are very highly correlated.
For simplification, we often ignore future housing payments in the rent v. buy scenario. We assume that your monthly out of pocket will remain the same, or will even out over time. In the rent scenario, you pay $X per year in rent; in the buy scenario, you pay $Y per year in mortgage payments. We assume that X and Y, either in the moment or as they accumulate over the life of the competing investments, are roughly the same so that we can ignore them for a CAGR calculation.
But that’s not true in the real world, of course. IRL, the cost of mortgage servicing remains roughly constant (barring a refinance), but the cost of rent rises over time.
This matters a lot to your wealth, because for nearly all folks for whom a “rent v. buy” calculation would relevant (ie. people who have a choice), the capital that they put into either a home down payment or the stock exchange will never be their only investment. They’ll invest $Z per year going forward as well. But $Z is affected by how much they have to pay for housing - probably the single biggest expense. So if a family has $50K left over after all their non-housing expenses, then their $Z - the amount they can put into the market - will be $50K - $X (rent) or $50K - $Y (mortgage).
In markets where rents and prices are rising faster than the norm, renting ends up being the worse choice for two reasons. The obvious reason is that the initial capital you deploy will be relatively worse off compared to had you invested it in housing, because of that price appreciation. But the other reason, which we don’t discuss in simple rent vs. buy calculations, is that you will have less money for all your future investment, because you have to pay more for housing on an ongoing basis as well.
There are pros and cons to both options. The primary advantages to putting your initial capital into a stock investment rather than buying are a much higher expected rate of return and much lower transaction costs. The primary advantages you get with purchasing a home are:
- Access to low-cost leverage;
- Advantageous tax treatment; and
- Insurance against future increases in the cost of housing.
None of those are small, though the second has declined in importance with changes in the tax code. From our discussions, I think you didn’t include any of them in your rent/buy calculations - which might explain your perspective on these things. But #3 is relevant to the riskiness of your overall assets. Buying a home exposes you to some additional risk of variability of long term returns (home prices are far less volatile over shorter periods, which has some advantages, but we’re not going to get into Sharpe ratios here), but it reduces your exposure to the risk of rising home prices. It’s an insurance product - and unlike most insurance, no skim to an insurance company!