But I thought bitcoin was invincible? 

Another illusion shattered.....

How big a test team do you need? There's 7 bn potentially out there?

Fiat is fallable, it decreases in value daily
Cash is fallable it burns gets stolen
Plastic is fallable you decrease in value every day
Bitcoin is fallable because (at the moment) it buys you nothing but more of the above 3 and some legendary socks and pizza if you live in new york.