Any time you make a purchase, of anything, you're trusting the seller. Leaving it in their custody is where you screw up. Imagine you bought bitcoin from me, but then asked me to hang on to it for you for free. Or a car. Or anything. It's absurd.
Ok, so we're in a spot where trust is literally required - but the ledger cannot be updated to reflect when that trust was broken or misplaced (at least not without falling back to an external power - namely: government).
So again - the entire value of the medium is predicated on having a legal system you can use to resolve these disputes.
Following - that legal system requires all sorts of control to actually resolve those disputes: Many of the things bitcoin advocates actively rail against are just methods of reconciliation (Funds freezing, reversed transactions, 3rd party control of assets, etc).
So either
1. The legal system will stop supporting exchanges of that medium (see: China)
or
2. The legal system will add back all those controls (see: Legislation in the US)
Basically - My entire point is that bitcoin only has value if current governments support its exchange, and they WONT do that if it's a negative to them (and it is, unless they can tax and control it).
