I don`t think that instinct has something common with stress. When you`re stressed you make mistakes trying to win more or to return your loses. It is not about instinct but mostly about greed and mistakes.
But you`re right that it is near with gambling addiction and we have to pay attention to such signals.
I quite understand you, stress and desperation can impair one's decisions, but this doesn't stop you from acting based on your instinct. No matter how stressed you are, the brain is still fully functional and might be so tinily and unconsciously trigger your decisions based on instinct. We should endeavour to know what instinct is so that it will not cause a misconception. In a clearer term,
instinct is a response to stimuli, so it always happens so long as your brain, cells and nerves are functioning and you consciously or unconsciously tasked them. This could even be hyperactive when you are stressed or in danger.
It depends on decisions. We can use instinct, but the same time we can just think so. And in reality it is our brain try to improve our positions and increase the bet or make additional bets. It is difficult to separate instinct from addiction in such situation. And, also, if you are losing, it means that instinct was mistaken in easier situation. It means that in stress situation it would work worse.
I understand what are you talking about but i think it is too easy to mix up instinct and addiction and it would be better to avoid believing instinct in such situations.