You're not wrong about the fire risk, but just to note, house batteries nowadays are almost always LiFePO4 -- which don't catch fire the same way LiPo batteries like to do.
They can still do so for other reasons, like a short circuit in the wiring.
Fully understood and agreed. That's why I bothered saving that for the second comment, because it's not necessarily that high of a fire risk but it is still a little bit of one. Having that much energy stored in that small of a package will always have some kind of risk of "what happens when that stored energy gets released in an uncontrolled and rapid manner?"
And that said, I do have lots of other somewhat beefy batteries around the house. They do a lot of useful things for me such as power my tools including my lawn mower, string trimmer, hedge trimmer, saws, etc. There is a massive one in the car parked in the garage. In these cases it is a useful trade off of that slight risk as I'm actually getting something normally useful out of it.
They can still do so for other reasons, like a short circuit in the wiring.