1.That assumes a certain level of sophistication 2. it applies to GME but not to most stocks either because options don't exist or they trade illiquidly.
FWIW: I had similar, but much less drastic experience with the low HTB fees at TDA. I think they may have been something like 2% or less when I began using them which looked very good to me, and one day observed 13% with like a 4% increase since prior day (I had ceased monitoring the daily rates as well). This prompted my transition to alternative shorting, as I was not in control of the costs.
That was not the issue. It was the OP's lack of knowledge about daily fee rate changes and not reading his emails concerning changes in the fee rate. His genuine response shows that he has learned from his experience. My guess is that in the future he will take trading seriously by studying trading and educating himself in what he is trading.
Looks like the fee was already 80% on the day he entered the trade.Way too high for my taste on a swing trade that might be held for several days/weeks. But I suppose everyone's "taste" might be different.
If someone chooses to lend and someone chooses to pay then what is the "scam"? Are you simply calling above X% a scam, or is there something more sophisticated?
Borrow fees can even go way higher. Check out REV, borrow rates did skyrocket to almost 1000 (!) %. And with T+2 settlement you keep paying even after you did close the trade.