The main obstacle to buying things you want in bitcoins (if someone is selling) is transferring your wealth into btc. Once people are "sitting on" enough bitcoins they will start using them to buy stuff more often.
Good point! And how much is Enough
IMO, there are 2 different measure:
1. I have constant BTC inflow which covers more than my monthly spending (500 BTC per month at today's price )
2. I have enough BTC that will ensure my living cost of about 3 years (15,000 BTC in today's price)
If none of these conditions met, I tend to keep accumulating BTC
Isn't this true for most of the people? And due to the limited supply of total coins, these conditions will never be met by most of the people, so most of the people will keep accumulating BTC