As title says, I think an expensive TV is a VERY VERY poor investment
My answer might be very, very difficult, for some to understand.
But it is actually the ('Buy cheap, buy/pay Twice!') cheap stuff, which (can be, but not always) is the poor investment, in the longer term.
For Example:
You save a huge amount of money, by buying a $0.49 screwdriver. It looks kind of good, until you use it, the screw head gets chewed to pieces and damages the item you were trying to open. The cheap screwdrivers shaft soon bends out of shape, and it needs to be tossed in the waste. You then buy a second one, for $9.99, a quality make. It works really well, never or almost never chews up the slot in screws, and lasts a lifetime.
My understanding is that many of the cheap TVs, are cheap because they have too few backlight LEDs, those LEDs are poorly/inadequately cooled, and fail prematurely. Somewhat pushing the owner to pay again and again for new TVs, every couple of years, or whatever the repeat period is.
tl;dr
It is cheaper to pay more, for something that will last a long time. Than to pay less, but it doesn't last very long at all, is somewhat useless, and you end up buying the higher priced item, as well, anyway.
So the more expensive one, is cheaper in the long term. If you buy a sensible long lasting TV. Even expensive ones, especially if poorly researched beforehand, can last for short periods of time.
EDITED: Big size reduction, too long.
EDIT2: As regards the TVs. I sometimes hear contradictory reports/stories/opinions on the internet. Many seem to be saying, if you buy the right/correct lower cost TVs. They can be good buys, even for the long term. So maybe the TV answer is not absolutely black and white (clear cut). As there are many claims, that some of the cheaper ones, are both reasonably good and reasonably long lasting.
So maybe the answer is (as already mentioned in this thread), do the research and get a good, long lasting one. Rather than ones that don't last very long.