I don't think that holding Bitcoin will lead to hikes in fiat valuation. In extreme case if everyone is just holding Bitcoin, there will be no price discovery at all.
One has to understand that because the total supply is fixed, Bitcoin works like a deflationary currency (albeit currently it is still inflationary, because new coins are released through mining). That makes people less likely to spend Bitcoin for non-essential goods. But as Bitcoin's buying power increases, there will be a point when people spend their coins. The last Bitcoin bubble also came with an increase in economic activity.
So, holding Bitcoin is not against Bitcoin. After all, not everyone holds Bitcoin eternally. At some point in time, spending Bitcoin will become attractive for almost everybody who still has access to his/her private keys. Bitcoin just doesn't encourage to squander money for non-essential goods like fiat does. In terms of resource usage that's a good thing.
ya.ya.yo!