People also wildly underestimate just how much taxes and maintenance can be, because they're not monthly - if you have to escrow taxes it's more noticeable, and if you correctly account for maintenance it's surprisingly high, even on relatively new homes.

The mortgage deduction only applies if you are not taking the standard deduction, and even then only the differential really applies (as otherwise you'd take the standard deduction) - something like 87% of filers will take the standard deduction.

Remember that if you have a copy of TurboTax or something similar laying around, you can do "what if" scenarios by inventing various 1099-INTs and playing around with them.

Even if a house is fully paid off, there are a ton of expenses that relate to ongoing maintenance of a house and property that really can add up--plus taxes and insurance as you say. The details vary by age, location, type of property etc. But $1K/month is not unreasonably high especially given that a lot of homeowners will have some sort of expensive job (some of which are admittedly upgrades) every handful of years or so which will easily chew through a year of that budget.

If the idea is you want a immaculate house with everything perfectly maintained then you can have high costs, but for example my microwave door handle busted off, I rigged up a fix, it looks terrible but not bad enough that I want to spend the money to replace it until it is completely dead.

The recommend replacement interval is useally a little pessimistic especially if you buy quality meterials and pay to do the job right.

I agree the parent lifetimes are probably a bit low. But the basic point that annual costs for a house/property are significant even if you can trim a bit at the margins.

My point is mainly maintenance costs are a lot more flexible than rent. You don't fix a washing machine, you won't have a washing machine. Don't pay the rent and your out on the street.

Part of me is also sort of thinking that each year I wait the heater I will get in the future will be a little more efficient. I've been thinking about replacing it since I moved in but just recently I'm hearing people in my area talking about heat pumps so I might see if I can give it another year or two and see if that becomes more mainstream and go that way.

If you're able to take a 30 year loan w/ a 2.7% interest rate and invest the rest of the equity, your house is cheaper than someone who buys it outright in cash.

The only time I would disagree with you, however, is for poor people. "Mortgage principle is not an expense" is correct over a long-horizon, but families living month-to-month that somehow managed to purchase a house are severely unlikely to be able to really capitalize on any value generated from that. I think your comment primarily applies to upper middle-class and wealthy people.

But the working poor are also the most likely to have to change jobs, which either forces them into a long commute or having to sell the house before they're really built any equity.

this isn't entirely true either. You need to live somewhere. Yes you own the equity, but it's always going to be locked away as "home equity". It has an advantage of giving you higher debt flexibility by taking loans out against it - but to say it is the same as banking cash as compared to renting is wrong.

Unless you downsize your living or sell the house without buying another one (which means you will be renting) that money is effectively gone as far as liquid cash is concerned

Make sure to not use the deduction verbatim, but calculate the amount that the deduction reduces your actual tax bill.