Why do we have traditions?
Thinking about them, they make no sense
Think of some popular traditions:

The tooth fairy giving you money
Shaking somebodies hand
Gift giving on Christmas
Celebrating Easter with eggs and candy

Why do we shake hands when we meet somebody? We don't know where their hands have been.
Why do we give gifts on Christmas, if the holiday isn't about gift giving in the slightest?
Why do we celebrate the rebirth of Jesus with coloured eggs?

They make no sense
Tradition has been a thing of wonder for a long time
Traditions come about, they change, they die out
Some stay the same
Some are complete scams.

Wedding Rings. Most believe that it is custom to buy a diamond wedding ring for your loved one before your outrageously expensive wedding.
That's not the case at all. The De Beers Diamond Cartel started advertising diamond rings as a tradition is 1938.
That's it. Less than 100 years
They also said that diamonds were rare and worth a lot.
They aren't either of those things.
They are quite literally just carbon that is arranged in a shiny way.
And in truth, they are rare. If we compare their rarity to dirt or oxygen.
In the gem world, they are the most common gem to be found.
They are just lumps of carbon.