You get shakey when you stand upbecause trees sway back and forth in even slight wind. It's hard to see but even movement of your feet of just an inch back and forthwith out your brain knowingcanreally throw off your equalibrium.

I don't get scared when I am up a tree 25 - 30 feetbut I do have to hold on to the stand sometimes because if it gets a little breezy I feel like I am dizzy.