Everyone's strategy may be the same in one means or another: buy low and sell high. But I don't assume everyone interprets that. And whether everyone's strategy is the same or not, everyone's purpose is to bring about a profit. So let's make a profit in a decent direction. Even if the strategy is not one, if it is profitable, it is nice for one's intellect. And even if it is a profit, what is the fault !!!
The fault that I can think of is that people wants to be the special one and that they don't want other people to have the same strategy as them even though as @kolbalish says, we have some minute difference in strategy, it makes them less superior.