Wow, that's a better abundance than I thought - I guess it really concentrates here - although still not that impressive. The major natural source of it and it's friends beryllium and boron is literally the nature particle accelerators out there in the cosmos, and the collisions they create, for example in our upper atmosphere.

The rest goes under "things other than abundance", which I did mention. Bismuth is a cheap element because it concentrates itself in veins and has limited applications, despite being comparably rare to silver. At the other end titanium is more common than all forms of carbon put together but is an absolute PITA to concentrate into metal and then manufacture into products.