So, don't sell to them instead, hold patiently and in matter of time depending on your goals and assets values, you could imitate them (whalers) or could even be one in the future.
Well if someone a retailer got a huge profits. Its normal that he sold it, nothing can change his mind for that. But that sold will lead to a new holder as someone will take his place. With bitcoin volume, I think it will not much truly go down considering how adoption happening therein. There will always be new players to take much pie of the bitcoin supply.
Maybe what he means selling in panic since if that's the case and they are losing their capital for doing that then I guess he's right. But if the seller is already reached on his target years and get already a decent profit for his self then I guess there's nothing wrong for selling their Bitcoin since this is what actually we intend to do. Our target is to get profit so everything seems really fine.
Also maybe if they target Bitcoin for retirement I guess its different story so there would be lots of debates towards this discussion since there's provably different reason will come out here especially people have different intention on why they buy their Bitcoin.
What we really need to avoid is to sell at loss since this is the dumbest decision we provably do.