The "idea" is a form of Arbitrage Trading (I believe it is called something like Triangle Arbitrage or something similar).
In theory it should work. But in practice it won't.
And it is not just fees. It is the fact that market always balances itself out.
And for this method to work you DO NEED a bot, you can not do it manually (speaking from experience
), because it is hard, you need to calculate the fee, profit, ... and you will make mistakes. Also you need to act quick, otherwise it is an opportunity lost.