What I noticed with Bitcoins and other Alt coins is that the market is very cyclical. It seems a bit like the prices in the stock market, just more extreme. The volatility in crypto currencies is higher than in stocks, that is also why we can make profits of a few hundred percent, whereas with stocks we are happy if we make 10-20%. As for manipulation, I don't think that its true for most of the investors.
The reason why we have such strong volatility because of so-called market manipulation. This has already existed since before, whales are playing tricks and make a huge profit but somehow, this also gives us the opportunity to ride with them and take some share with the whales. It really becoming unpredictable because nobody tells us what they gonna do next and for the fact that some are selling and buying, that it adds more movement to the price.
I'd never think that manipulation is bad but for me, even though the risk is high, it helps me to generate profit unlike if we just have a stable market.