They have to make the thumbnail attractive so they're going to be clickable to their viewers. But I don't buy those thumbnails and I only watch those videos that I'm really interested at.
But most of them, I've got no interest anymore because of how crowded they are.
Same goes for google ranking, same goes for articles, basically everything gets listed higher because of click rates, bouncing also matters, if people click and leave right away without watching or reading, then it doesn't work well.
And that's why if they've seen it effective, actually, it's really effective for those video makers that has contents about cryptocurrencies and for other contents.
It's like became the standard of thumbnail and clickbaiting on social medias not just on YT.