Two types of traders can stay profitable even in a bear market, the first one is futures traders because they can short the assets and gain profit from that as their prices drop, and the second one is scalpers because even in a bear market, there will be price swings, and when swings happen, scalpers can buy lower and sell high to make quick profits from their moves, and even though it might not be much profitable, it at least gives them something; as they say: something is better than nothing.
For investors, the bear market is only a good time to buy and fill their bags as much as they can so that they can sell when the bull run is here. Other than that, they can't do much because they tend to make a profit in the long run, and in the short term, ups and downs shouldn't affect them much, as they usually look for better prices to buy only.