Well weddings aren’t important to everyone. A lot of people are interested in being married, but the actually wedding itself doesn’t mean as much to them.
But the point should be, that a nice wedding is important to YOU. You don’t need to convince him why it is important to everyone else, just convince him why it is important specifically to you.

Honestly, I don’t care for weddings at all. They’re a waste of time and money. My boyfriend, on the other hand, thinks the way you do. He wants to get married and obviously doesn’t consider it a waste.

So yeah, that “Every girl knows what I’m talking about” line doesn’t work.

I’d like to know those reasons too because while I would like to get married someday, I don’t want the pomp and circumstance of a traditional big wedding. I think it’s a waste of money as well. Why buy the dress you’ll only wear once? Why all the flowers that will only die? Why the color coordination on every little thing? The only real important things about a wedding is the vow to love your partner forever and sharing that moment with friends and family. It shouldn’t matter if you get married in jeans and a t-shirt, or have a cake from a grocery store. The rings don’t matter either. I know I don’t need a physical symbol to remind me of how I feel about my partner and the promises I’ve made. I’ve never understood this so-called female obsession.

I’d open with that.

Once another guy with a bit of experience that he trusts tells him “the wedding is all about what the woman wants” I’m sure he’ll come around.

Offer up money saving sacrifices to save money like “I’m picking up an extra shift to help pay for the wedding” or “I need to cut back on for the wedding”

As long as they don’t affect his lifestyle (unless he offers).

Remind him how good things will e after the wedding.