for example time and time again we have seen altcoins that had no reason to rise, go up a lot because someone was pumping them and that pump changed the sentiment to buy because many investors are well aware of the situation and want to join in and make the quick profit.
I don't think Bitcoin is particularly manipulated. I've found that reading sentiment and commitments of traders is really useful for BTC, just like it is in the "real" markets like forex. To a large extent, this extends to ETH and the more liquid altcoins.
Much of the altcoin market is very "pumpable" though, because liquidity is so low. I'd say the less liquidity a market has, the less useful sentiment reading is. With low volume / low market cap coins, a single whale can completely change the available supply and demand. That's not possible with larger coins.
what i said above is about the cryptocurrency market in general not bitcoin market. otherwise i agree with you that bitcoin price is not particularly manipulated although manipulations exist in bitcoin always attempting to sway the price in their own favor.
as for other altcoins it is depending on the coin itself. i would disagree with saying ETH is not manipulated, in fact i believe it is one of the most manipulated coins in the market at the moment mainly because it is centralized and the foundation's livelihood depends on ethereum's livelihood and that is (in the current newbie-filled market) determined by having high market cap which is guaranteed by having a huge supply and a rather high price.