I try to fish around for good J fares, but if that isn't possible, I'd gladly pay more to sit in 9-abreast 777, or in Y+, instead of a 10-abreast 777.
But that shouldn't change the fact that POS should be forced to pay for another seat. As I and many other FTers have noted earlier -- I paid for a seat, not half of it. POS who refuse to purchase another seat should be denied boarding.
My intention isn't to fat shame anyone, but if I find myself squished, well...I'm afraid I'll have to complain.