I really wanted a large screen, so I got a projector with a 100 inch screen for it. Though you're definitely right about light being an issue, I can't quite get that size with tvs yet, at least not in the same price range.
I went as far as considering rear projection.. Just cut a 100 inch hole in the wall.. But by the time this was happening.. Prices have come down enough that the labor was too much ..
70" 4k tvs are $1000 on sale these days.. a good one can be had for $2500, a good projector with 4k and good blacks starts around $2500 add in cost of motorized screen, room decor, lamps down the line.. potential repairs.. it's about the same price..
I've seen the 80 inch go to $2500