Gambling, when it comes down to it, is a zero-sum game. In strict competition, what the loser loses and what the victor gains are exactly the same amount.
Combined, the total wealth doesn't change; take for example two people each with a wealth of billions betting against each other, if you extend the gambling time indefinitely, even if one of them goes bankrupt completely, their combined wealth would not change in the slightest.
For the disciples of the Yun Clan, such "zero-sum" business is considered the worst kind of business.
Even worse than the "zero-sum" business is the "negative-sum" business.
Take gambling for instance, this time it's not just two people betting against each other, but there's also a middleman who ensures fairness. Every time the winner wins a hand, they give a little "tip" to this middleman.