Did you have an engagement ring AND a wedding ring?

I'm trying to understand why the hell people buy an engagement ring and then a completely different ring and band for when they get married? What's the point of that? Like why waste more money when you could just buy a matching wedding band to go with the ring? 🤦🏼‍♀️ super easy to save that $200-$1000 to go towards ur honeymoon...

UPDATE: Y'all are misunderstanding what I'm saying. I'm not talking about the wedding band, I'm talking about people having an engagement ring, solely and only for their engagement - and then a 100% completely different SET (Ring and Band) when they get married. Like not the same ring whatsoever?