If I'm using a retail broker, and my account makes a lot of money there, is anybody who works for that broker going to see what I'm doing and tell his hedge fund buddies about it? Are there any privacy laws about that sort of thing?
It's too late now. Since you mentioned that your strategies are secret, (which you have been using all along) on this forum, your broker will now notice it here and will forever take every measure possible to assure you no longer make money, so you stop trading and they lose your business/commissions. Time to retire now, go fishing and never trade again.
I had a really good strategy shorting pump and dumps in May through October, but I talked about it too much, bragged about my Sharpe ratio of 6, and then in Oct-Dec it got overcrowded to the point that it was much harder to find targets, and now in January it's blowing up with WSB manufacturing squeezes on all the heavily shorted stocks. Every trade that gets overcrowded blows up. Talking your book is minus EV in the long run.
Sounds pretty standard to me. The market adapts on its own, unless it's something super specific I doubt that you talking about it was a factor of the edge's demise.
My goodness! This question has been asked millions of times! Brokers are totally not interested in our trading strategies because brokers don't want their minds to be contaminated! What shall we do if the next person asks a similar question?