Manipulation patterns are obvious, but indeed, without actual proof we can't say it's actually happening, even though we for sure know it happens.
Think about it, if multi trillion dollar asset markets are subject to manipulation, don't you think the same entities will throw in some pocket change and play with Bitcoin in the same way? I think it's actually pretty foolish to not think there is manipulation going on. The market is heavily being manipulated right now, and this manipulation has been going on since the very beginning of Bitcoin being a tradable asset.
Bitcoin's market is extremely illiquid, especially in traditional market standards, so just a small amount of capital from institutions is enough to make Bitcoin go beyond the moon straight to Jupiter. If we also add that you only need to manipulate the price on one or two main exchanges, then they can even blast the price to Pluto.