[runeks]

> Millions of consumers may use Stripe/whoever to send $$ to millions of other consumers, but that might all be handled by a (relatively) few BTC flying back and forth in batches on the back-end, which doesn't necessarily require a large per-BTC price.

That depends on what you mean by "large per-BTC price". It requires a certain minimum BTC price to move a certain amount of money when settling in bitcoin. You can't move $1M USD in one Bitcoin transaction if a single bitcoin is worth 1 cent and there are only 20 million of them. So the bitcoin price measured in a certain currency limits the maximum transaction volume for that currency when settling in bitcoin.

Secondly, and perhaps more importantly, it requires great liquidity/market depth. One must be able to buy or sell a lot of bitcoins without affecting the price. This is the essence of money: a high-liquidity commodity.

> I guess I mean "valuable" in the intrinsic sense, not the financial sense.

When settling in bitcoins, they need to have value in "the financial sense". That's a requirement.