@Doomer He wants to convert the money to DP.
He can't just raise the prices at the inn, that won't get him more income since it'll start to become something only A ranked adventurers can afford. A major draw of his inn is the low prices, but he benefits more from the DP income since they are within the dungeon's influence.
And selling items....he wants to work less remember? Making stuff so he can work less later is one thing, but making stuff all the time routinely is a no-go.