Of course they can't be unnoticed for a long time. Remember Jamie Dimon? they were caught buying shit loads of bitcoin after he attack it for several days to bring the price down so that they can buy it cheap.
Later it we find out what they did and they make tons of profits as well. So its really good to see what the whales are getting up to. But for a simple pump-and-dump groups, looks dubious, because they really get out early and exit on time before someone notices what they did there.
Good stuff, so he used his influence to manipulate the price and then bought it.
How was he caught buying bitcoins though? Did someone notice a large transfer and then suggested it was Jamie Dimon?