Why does someone take a 12k mototcycle and drop 30~40K on customizing it?
Why does someone take a 10K shotgun and have 50K worth of gold filled hand engraving done on it?
Why does someone go see a luthier and commission a 25K custom bass?
The same simple answer fits for all the above as well as any other question about how someone else spends their money.
Because they can and they want to.
The value of the item to it’s owner is whatever they see it as, and without putting too fine a point on it, it’s nobodies business or concern what that value is. Unfortunately it seems to be a popular pastime to judge others by one’s own standards or limitations. Just because you can’t understand why does not make it wrong, wasteful, or egocentric. It just makes it a personal decision by someone else. You are no more required to like it than they are to need your approval to do it.