Because Bitcoin is not for trading, Bitcoin is for long term investment.
I don't think it's bad for trading, bitcoin also has volatility that is worth trading. Traders can determine their favorite coins to trade after some evaluation. Even on some exchanges you're allowed to use up to 100x leverage, if the Op is good enough at this then he can generate profits bigger or faster than long term investments.
I agree with what you said: if a trader has a deep knowledge of trading, he can definitely make more money compared to long-term holdings if he does short-term trading in the crypto space. Even in BTC-USDT, it will conduct trading activity on the exchange.
If you are an expert and you are one of the scalpers who can make a profit every day, you will definitely become a rich person after just 1 year of exploiting it. Where and how easy is the profit to be made?