If anyone thinks that somebody's wedding is 'wrong' in their measure (too big or too small), well, in the words of a great 21st century philosopher: "scuba".
And yet, you've implied that not spending money on a professional photographer is "wrong" or "trivializing" the importance of the image.
My thought is that it's an unnecessary risk. If it works- you have saved a bit of cash that will be spent on something else soon enough, but if it fails you have forever lost the opportunity to have images that you really really should have for the rest of your life.
You're speaking as if this is a life or death decision to make, and also assuming that others place the same importance on the images as you do. I'm not saying the pictures have no value - of course they are, as they are reminders of a milestone event that most people want to remember. But it's no one else's business what form those pictures take. If someone wants professional pictures, fine. If someone wants snapshots from table-top Instax prints or disposable film cameras or iPhone snaps, then that's fine, too. They're not cheating themselves out of anything - they are creating the kind of images that will continue to resonate with them. And there are also those who just truly don't care that much at all about the images. Their reminders of the important event do not lie in an album or picture frame, but in their actual life with the person they chose.
Personally, I've never had any emotional connection to any "official" professional photographs. They leave me cold. Why would I spend thousands of dollars to get images that leave me cold?