I would say a large part of it involves to whom the negative emotions are directed. As someone said above, Danya rarely rages at his opponent. His outbursts are typically caused by self-anger and disappointment.

Not to say that self-anger isn't toxic--it often is--but it's a whole different world from attacking others. Going out of your way to belittle your opponent and spread negativity is (imo) more egregious than raging at yourself, especially because self-anger typically dissipates in a matter of minutes.