The garage door is a fun one. They are heavy, and there’s a spring at the top to bear most of the weight so a person (or electric opener) can raise or lower the door with modest effort.
That spring experiences one fatigue cycle every time you raise and lower the door. Two cars coming and going twice a day (plus various other cycles, e.g. taking the trash out or mowing the lawn) means roughly 1500 cycles a year. 15,000 cycles in ten years. Our spring broke a couple of years ago as I was lowering the door. With the door almost fully lowered the spring has a lot of energy; it sounded like a fucking shotgun going off in my garage. The kicker was that the spring is fixed in the center, and the break was to one side - so it only let go of one side of the door, and the whole door got badly racked. I managed to muscle it open and get my car out for work the next day, but we had to get it replaced right away. Can’t remember for sure, but I think it was on the order of $1000 for a two-car-wide door.
Sensible. HVAC can be costly, and depending on where you live, the loss of cooling can make your home extremely unpleasant, or the loss of heating can be an outright emergency. Several years back our AC was terminally ill (occasional icing on the evaporator, + screaming dry bearings in the condenser fan), so we opted to replace. Contractor noted that our furnace was 21 years old, so we opted to replace that at the same time. Bill came to $5K all told. We were OK with that, but it’s not hard to imagine some people having a crisis if they don’t have funds set aside for sudden home repairs like that.