Since the cost of Ethreum gas is expensive then many projects that use the BSC network because of the cheaper cost and very easy for us to use, but this is not a momentary development for the BSC network and this will happen even though later the cost of ethreum gas is back down, and I am very sure the two coins will continue to compete both from the price to cooperation with the bounty project.
The issue about transaction cost is very related to scalability issue.
Right now ETH Developer are working to increase it, ETH network only can process up to 2M transaction per day.
https://ycharts.com/indicators/ethereum_transactions_per_day#:~:text=Ethereum%20Transactions%20Per%20Day%20is,91.93%25%20from%20one%20year%20ago.
Hopefully it will increase to 10M transaction or more after ETH 2.0