It depends. I would argue that even if people hoard 90% of their bitcoin holding until a large enough percentage of the world adopts it to increase the velocity and stabilize the price, if bitcoin enables countries without banking infrastructure to compete globally; it would actually increase economic growth. In other words; Bitcoin the enabler.

I may hold more BTC than I spend, but you bet your ass if bitcoin enables a farmer in Africa to sell me cheaper goods than I can find at home, I will spend bitcoin to import it.