If I'm willing to spend $500 on a computer, I'm willing to spend that money to get something of value back; doesn't mean I can just tolerate the loss of money without gaining the objective. I also have low risk tolerance, personally, so I get the extra year or two of warranty on that computer for $50 because I like knowing that while it's not quite obsolete, yet, I can get any part of it replaced and it won't cost me half the value of the computer plus my time figuring out how to do it.
So I can totally understand how someone who is spending any significant money on a wedding (and with a large family and/or a culture of larger-wedding traditions) even if it's just $5k or $10k, would be willing to drop $100 to make sure that if there is a family tragedy or a weather event (you can't predict these things a year in advance when you have to book the venue, if you need one!) they can keep their money and hold the wedding another day, instead of losing it and getting nothing. Even if it is generally a financial loss, it is a relatively small one for a lot of psychological benefit, i.e. peace of mind.