I got my mortgage at 2.5% interest. The mortgage was about equal to all of the cash I had before buying, and I'm pretty sure I could (and should) have gotten a much larger mortgage before buying. Mortgages are essentially the only way for ordinary people to access that kind of credit. That's why buying a house is such a good deal. No one's lending an ordinary 30-year-old hundreds of thousands of dollars at 2.5% interest to plow into the S&P 500.

Of course, this kind of credit is _incredibly_ risky. People don't think of it this way, but a mortgage is essentially a massively leveraged bet on your local housing market. Which is already gives your risk profile an incredible lack of diversity. The most valuable thing you "own" in the time of your life when you buy a house is usually your future earnings potential, and your house will be the second most valuable thing you own. The thing is, both of these things are highly correlated with your local economy, so buying a house doubles down on your already high exposure to local economic conditions. People think of owning a home as a kind of boring, safe, low risk/low reward investment, but it's really exactly the opposite.