I don't think that can be applied to Bitcoin nowadays as amateur traders don't dominate the Bitcoin market. They have some influence but they definitely don't dominate it. If you were talking about the past, maybe the 2016-2017 market I could agree, but not nowadays.
That said, it must be recognized that they have influence over the price, especially when they are over-leveraged and at the slightest drop in the price they get margin calls, thus lowering the price even more, as we saw recently.
I think quite the opposite. Bitcoin has always been driven by individual investors, it's only very recently that institutional investors starting getting involved. Whether individual investors still drive most of the trading is debatable, but you'd have to have data to support an argument that what has always been is no longer.
But it always been pump when the hopes of majority us so high thats why we can see a huge price increase if there are certain hypes spreading on mainstream media. Also we can see so many crybabies after the market crash so we can really say that those guys are contributors and somehow they are one of the reason why bitcoin can be consider as bubble for now.