Currently worth $70 Bn, Is this a lot?
Personally it seems quite a lot for a fairly untested currency.
US gold reserves currently worth something like $300Bn, the largest in the world (though it's no clear if anyones checked its there). All this is less than a company like Google but still $70Bn is a lot of money.
For the bitcoin price to rise a lot of money would have to flow in. Right now it seems like every grandma and her dog is being persuaded onto the bitcoin bandwagon. Is this not a sign of an impending crash, in which those at the bottom of the pyramid get burned? Is the bitcoin rise sustainable? Where will the money be flowing in from? Will shops have to start selling bitcoin investment scratch cards over the counter to keep the price rising?
I'm keen to head from people who can make arguments based on fundamental economic principles, either way.
Chinese ban, Chinese manipulation. Dangerous restrictions, these are all preventing bitcoin to reach higher market caps for sure. But technically, there is not mathematical limit on bitcoin's cap.
I think as with anything, you can have two outcomes. Growth or crash. With the Chinese news, you see a bit of a drop. You can consider this our "crash." Since there is a fair amount of backing as can be seen in OP's example of every grandma and her dog (made me laugh), there is a potential for growth as there is a general interest from those who are trying to hop onto the Bitcoin chain.