It didn't happen overnight, but there are a ton of modern applications for platinum. Many of them use it as a very efficient catalyst, many reactions can be massively speed up or only happen when platinum is present.

Essentially, they had to figure out how to isolate it from other metals entirely (you have to alloy it and then reduce it with acid) so it would have consistent visual and material qualities and could be reasonably worked. From that point on, the fact that it was both rare and pretty to look at made it immensely valuable, same basic reasons as gold, except NEW and EXCITING. Inside of a decade it went from worthless to the next big thing.

Aluminum had a similar treatment when it was discovered, becoming immensely valuable because it was pretty and novel, though its value dropped like a rock as easier methods of refining aluminum were discovered.

It's an important ingredient in credit cards. Of course you have to invent credit cards first.

I remember reading this article a few years ago, about an asteroid full of platinum in our solar system (2011 UW158). The article stated that, should we manage to bring the whole asteroid back to earth, given the amount of platinum in it, it would trigger an economic crisis given that platinum would become a "junk" material, in term of supply and demand.

While the outcome is purely theoretical for now - given that asteroid mining / wrangling ain't a thing currently - it really is telling when most people agree that with our current economic system, which really is for the greater good (/s), a surplus of a useful mineral would end up making a lot of people hungry.