The wealth of the city of Potosi is not a complex tale of economic interaction and gentle growth. The mountain behind it is made of silver - it's worth a fortune. End of story.
Despite the best of the silver being long gone, the mines are still operated by collectives of individual miners. Don't believe me? Go and see for yourself!
Because you can. You can go and tour the mines, meet the miners, and get to know what their lives are like. You also get to blow stuff up, and that's always fun.
First the tour leads you to the miners' market, where you stock up on presents for the miners, such as coca leaves, dynamite, and soft drinks. The soft drinks are important, as it's very hot (approx. 30 degrees C) in the mines and the work is very hard. As such, wear as few layers as possible, despite the chill outside.
The mines are also very cramped, so expect to have to duck, crawl, or wriggle your way through. They're wet, dusty, and filthy as well, so don't wear your best clothes. Most agencies will give you protective gear included in the US$10 price.
Naturally, this means the mines are not suitable for claustrophobics, those with breathing difficulties, the elderly, small children, those who are rather large round the waist, or those who don't like getting their clothes dirty.
But if that isn't you, then do go. Dodging two-ton trolleys of ore and chatting to sweating miners is a unique experience that will get you closer to the coal face (so to speak) than you ever will again.