It is a disadvantage but at the end of the day they are the ones that are going to suffer from it and not us, institutional investors for the most part understand this which is why they invest in bitcoin only, retail investors on the other hand see the market cap and the price of bitcoin and while they know they can still get profits they get seduced by the promises of altcoins.
We know that a few of them will actually make more money but the vast majority are going to lose everything they have in the process and for some reason blame bitcoin in the process, and while this is sad they were the ones to take such decision and as such they need to learn to live with the consequences of their actions.
Altcoins are still in the bubble zone and the situation may remain like that for some time before the bubble bursts. When the correction occurred two weeks ago, I was thinking that it will result in many of the altcoins going back to the fair valuation. But that never happened. There was not much change in the Bitcoin dominance, which means that the altcoin market share remained unchanged. Those who do enough research knows about this and they would prefer Bitcoin for investment. But some of the new users may go for shitcoins such as XRP and DOGE, influenced by the massive propaganda that is being unleashed in the social media.