They can, if you find a good professional trader who perfectly knows the market and sells his signals for expensive.
Yeah, that is, if that professional trader are willing to share his knowledge, but I'm under the impression that those who have made a lot of money are not going to have their secrets on the public.
Otherwise, you run the risk of getting into repeaters or weak traders, who, although I understand how to interact with the market, will not be able to dodge the next unpredictable market movement, and all accumulated savings will be lost.
There are a lot of so called experts who claims to be, that's why we should be very careful on who we follow or. trust in crypto trading. Because we are not sure, maybe they are just hiding, but behind they are just like you and me here, average bitcoin traders.
As a rule, with a stable BTC, the signals work almost flawlessly, but at some point a strong movement can lead to large losses in all positions.
Swing traders are very dangerous, the safest to do is just buy in dip and be a long term holder.