Coins with high supply are the most manipulated coins by whales. Why? Because its so easier to manipulate them. So speculative prices are always possible with them, we all see really bad coins doing 1000x in past.
How come it is easier to manipulate them? It's not like you need to poses one whole coin. You can split it up into like 8 or more decimal places, so what you are saying is definitely not true.
Only correct thing is, that a lower marketcap coin might get manipulated easily, because they are cheaper, so you can actually own a majority of them. As the market cap gets higher, this gets harder.
Overall, higher market cap means less extreme gains. But not always. We have all seen Etherium, that has been in like top 10 or top 5 gain crazy, almost x100 value in the last year.