It will be a profit to some people with huge capital to go for Arbitrage trading, one can buy on Binance and still sell on that same Binance; or buy on Binance and sell on KuCoin but the transaction fee might take the profit if you have low capital.
You can even use Binance to do it, but I do not know if that is against their terms of service, but I do not think so. I can see the opposite on OKX:
There are some Nigerians that can use this to make money. In short, they are using it to make money.
For the fee, sending from Binance to OKX and some other exchanges can be though lightning network. Bitcoin transaction fee on OKX is one of the cheaper on exchanges.