The 744 for example is a much more profitable aircraft full than the A330, to have full aircraft you must have a strong market.
I could fill a B744 with $1 tickets and go broke.
You need both a strong market and a reasonable
yield per seat to make money.
Yield
and butts on seats is the key to profitability!
B744 with rollers will be rare soon but unfortunately the "hog" will be with us for a long time to come.
Boeing twins rule OK !!!!