[throwaway22032]

Mortgage rates where I am are basically always within 1-2% of the risk free rate and less than most investments return over time so this isn't really true.

You have a very small opportunity cost, which reduces your risk of default to near zero.

Holistically, you can then take greater risks in other areas and end up longer term positive.

To me your argument is like saying that an airbag, or a crumple zone, or a seatbelt, increases the weight of your car, and therefore fuel consumption, and therefore it's expensive. It's true but only in a pedantic way, when you need it it suddenly goes from being "expensive" to a huge net positive no brainer.

[constantcrying]

What? This makes no sense, if you want to have money in case of economic trouble you obviously do not invest it. This is just contradictory, so you have to actually have the money in a savings account.

Over the decades you are paying off your loan you pay tens of thousands of dollars for having that savings. Each month of having that safety net will cost you money, the result will be that it takes you many years longer to pay it off.

I am not saying that in moderation it is a bad thing, but it certainly has serious downside, especially if you are tight on money.