A lot of people indeed have bio unavailable copper. Usually, if you're low in copper that means you have low ceruloplasmin - copper binding protein - and thus, your body cannot utilize the copper releasing all this free copper into the blood stream which causing cooper toxicity. I'm one of those. My hairesume analysis shows low copper and ideal zinc. So the supplements I'm taking contains zinc and copper. It could be harmful of I only took zinc.
Yes copper is a stimulant to the adrenals. But our body needs balanced levels of copper.
It's a very complicated subject as its hard to find good info on copper bio unavailability.