Trading is very risky than people think until they are losing and become addicted to trading before they will realize this. Some people have known bitcoin since some years ago but they are still struggling. They are struggling not because they did not have money in the past but just because they are trading. They wanted fast money and they lost and lost several times.
I don't believe that someone will be trading for many years and still haven't understood how to trade to make a profits, as the trading isn't working for them why don't they stop and do something different. Anybody that has been trading for a long time as you said and isn't making profit but still trading, that person doesn't have value for their money and deserve to lose it to someone different that'll value the money and use it responsibly. I just returned back to trading therefore I haven't been trading for a long time but if I trade for few months and I'm not seeing any progress, instead of me wasting more money, I'll use that capital for something different for good.
The answer would be easy - they just don't learn from their mistakes.