Large moves are not “manipulation”
The "price" of eth isn't changing as rapidly as many these posts seem to imply. When a large dip happens or a large rise happens very quickly, it's a result of a lack of liquidity in the market. If someone (or in reality many people), want to sell a large amount of ethereum they start to eat through the limit buy orders on the book. Once market sell orders overwhelm limit buy orders, the price starts to drop rapidly. The same thing happens in reverse. This is not "manipulation". That's not how markets work. It's a fundamental supply and demand equilibrium. It drops quickly or rises quickly due to a lack of liquidity at the current price.
The most "manipulation" that can happen is that someone sells a lot of eth quickly to drop the price., hoping that others will panic sell, and that market makers will come in at the new low price so they can rebuy. People do this, but it's extremely risky if that's your actual strategy. What if you unload 20k eth, dropping the price a lot, and some other whale comes in while you're doing this and rebuys? Then the price is suddenly a lot higher than a good chunk of your sells.
Relax. This is crypto, it's going to be volatile.