what seems so patently obvious to several dozen other posters, but,
"buying refundable tickets on numerous sold-out flights" has me completely puzzled.
HOW, pray tell, can one buy a ticket on a sold-out flight? If there are no seats, there are no seats, and I assume one cannot throw money (even at a UA TA!) and say, "Oh, that's okay, just sell me a ticket anyway."
Otherwise, if one buys a refundable ticket and then voluntarily (or in-) is denied boarding, where's the illegality in that? Anyway, how can one tell a flight is about to be sold out and/or be guaranteed to be denied boarding? From my experience I've only volunteered not to fly, never been "forced," regardless of tix type.
If my lack of understanding makes me out as incredibly naive, dense, or careless, so be it; someone please PM me.