You don't have to be a silk road vendor. You just have to be selling and buying both, then you can make money on the spread, which can be several percent in P2P markets.

This.

When I lived in Argentina, the maximum amount of USD you could pull from an ATM was $200 per day, dispensed as 600 pesos. That was at a government-enforced 3 to 1 USD to Pesos. The price on the open street market was at least 9 pesos to the dollar.

So, say my rent was 3600 pesos a month. Technically USD$1200 at the official rate, but only USD$400 at the blue rate. It was better for me to take a boat to Uruguay for $100 round trip, plus a hotel room for the night, to get dollars out of a bank there and trade them on the street in Argentina.

Okay, that's the setup of what I was doing. But with Localbitcoins I found this kid who would prefer to hand me a stack of USD$1000 than Argentine Pesos, for BTC traded private wallet to private wallet. He was in his first year of college and he'd just opened a money exchange office in a shopping center.

One day I asked him "where do you get all those dollars, and what are you doing with the Bitcoin?" He told me, most of the service goes the other way. You see, they needed my Bitcoin, because in Argentina, government employees at that time were allowed to take 20% of their income in greenback US dollar cash.... at that amazing government exchange rate of $0.33!!! So naturally they wanted to get it out of the country, not keep it in cash. But Argentina also would not allow you to take more than $500 out of the country. My friendly high school Bitcoin entrepreneur had a solution: Take their dollars and exchange it for Bitcoin, then send the Bitcoin to a friend in the US who would change it back and depost it into a US bank account (for a 5-10% fee). This avoided the export controls and allowed them to offshore their cash without trusting the Argentine banks, which were well known for defaulting on their customers.

The only question for my friend was what to do with all this USD and how to get more Bitcoin with it, which was where expatriates like me fit into the picture.

This is why I believe that the real and only value of BTC is in avoiding currency controls, and it'll continue to have value as long as those controls exist in places, but the closing of the open markets and the end-to-end tracking of ingress and egress points makes it a lot less viable than it was.