When the Bitcoin market grows large enough it will begin to stabilize more. I was around Bitcoin when you could crash the price, which was around $5-8, with about $10K using 8 to 1 leverage (or about $80K) on the forex trading site Bitcoinica (now closed).
You can't crash the price now with only $100K, because the market is so much larger. Bitcoin has a market cap now of over 1 billion dollars, so it takes many hundreds of thousands or more to really manipulate the price.
Volatility won't matter too much anyway because bitcoins can/will be used in the future as a transactional currency, where people only hold them a few seconds to do a transaction, then they are changed right back into something less volatile like USD, or, even better, gold.