This is simple, very few investors are humble enough to accept that they are going to make mistakes from time to time, so when they lose money instead of accepting it and trying to find a way to improve themselves they take the easy way out and try to blame others for their losses, you may think this is something that happens only to amateur investors but even some of the most famous investors do this and blame others for their losses, and when we take into account that bounty hunters are known for dumping their coins as soon as they can it is easy to see why they are blamed when a coin dumps.
It is true, they repeat their mistakes from time to time. Buying at highs when they should not, and don't buying at lows when they should do it; selling at lows when they should holding, whilst don't selling at highs when they should selling (due to over expect that their coins will move much higher). Then, when they miss chances to take profits at spikes, and get losses by buying at highs, they blame on developers, on whales. Such guys will repeat their mistakes again when they get other funds to invest in crypto.