Why marry the same person over and over? Isn’t once good enough?

Recently just announced in the news Matt Damon and his wife Lucianna are having another wedding after 8 years. Are they celebrating getting past the 7 year itch?! They aren't the only celebs who do that.

Nick Cannon and Mariah Carrey do it every year on their anniversery. Heidi Klum and her then husband Seal used to do it every year. Look where they are now?

I just don't see the point. I guess because they have all of that money they can. I could think of a whole bunch  of better things they could do with their money. If you have that much money give it to the poor or build some houses for the homeless, send a kid to college that can't afford to go.  But wasn't the first one good enough, did it not mean forever? That is the whole purpose of getting married!