I agree that if the price rises too quickly, we're much more likely to get a sharp correction/crash, as it true with pretty much any financial instrument.  Overall, though, while bitcoin's rise this year has been very fast-paced, there has been a lot of good consolidation and some dips that take some of the froth off of the market.  At least on a percentage basis, we have yet to see anything like some of the insane increases in the past, like near the end of 2013 when price quadrupled in about 3 weeks from around $250 to over $1000.