I think there is a hypothesis going on, that the Earth has an above average quantity of gold because of some novel cosmic event, e.g. neutron star activity that just happened to be in our neighborhood ~5 billion years ago during the formation of our Solar System.

My layman understanding of Astrophysics is that we understand things up to Iron pretty well. Beyond that there is a lot of conjecture.

I've never heard it explained very well, the best I can find is a 40 year old PBS show. Thanks to Virginia Trimble.

https://youtu.be/0byMj2VrT2g?t=565