The exact extent of the problem is unknown, because many victims are embarrassed that they spent so much money on what was essentially a hoax. Many people actually spend more money once they realize that they've dug themselves into a hole, thinking that winning the 'prize' is the only thing that can save them now. Instead of a savings account or retirement fund, they end up with garages stacked floor to ceiling with junk.
The truth is that legitimate sweepstakes will never require a purchase to win, and buying products will never increase your chances of winning. Every legitimate contest and giveaway will include a sentence in the rules that looks something like this:
YOU HAVE NOT ALREADY WON. NO PURCHASE IS NECESSARY AND WILL NOT IMPROVE THE CHANCE OF WINNING.
If you or a family member are a victim of this kind of sweepstakes scam, contact your local attorney general. In some cases it is possible to recover the money that has been lost.