yeah you can get decent returns when you sell liquidity to loop or on marketplaces etc, but thats not really a repeatable process unless you have endless bitcoin

amboss is throwing around some numbers between 1-4% but thats all based on anecdata and thats the point, it becomes better with large infrastructure - @LNBϟG is sharing his numbers somewhat frequently so thats a good start to dig into this

here's an interesting thread