Well said has!
It's the same herd mentality that sees people flocking to the motorways and airports in their millions every Christmas, Easter, summer and Bank Holiday. They are supposed to be travelling for enjoyment and pleasure - but I don't see one person in the motorway jams or packed terminals who actually looks like they are enjoying themselves! So why do it!? My wife and I travel, but it's always in the quiet times of the week and year when airports, hotels, restaurants and very quiet (and much cheaper!) than holiday times when prices are put through the roof. It's a pleasure then.
It's the same with the herd flocking to the shops in such droves they can't even find a parking space! If people do want something from the shops then why not go in the first week or two after New Year when the shops are peaceful and quiet and it's a pleasure? Most people at the sales wouldn't have planned to spend any money if they hadn't joined the herd. It just seems to be spending for the sake of spending.
As you say, these people are nuts.