You're right. It's often NOT nurturing and it *IS* like a bootcamp at times. I'm thinking of those weight loss bootcamps... someone uses all their willpower to successfully snack on natural foods and avoid things like ice cream and cookies, and then the coach yells at them for eating too many carrots instead of celery.
I don't like this approach myself but it doesn't seem uncommon in nursing school. So make the best of it possible. Find a way to make it motivating to you.
You can take it as a challenge. They think you're not up-to-snuff? Well you'll prove your worth by always being two steps ahead! If they don't seem to want to teach you, then do whatever you can to teach yourself and find others to teach you (classmates can help each other since each have different strengths and weaknesses). You will run across a lot of unsupportive people in your life as a nurse and in general, so might as well start now not letting anyone else determine your worthiness. Even failing a class, or being told "I don't think you're cut out for this" doesn't mean you can't be a great nurse. That's up to you. If you really want it, you'll make it happen eventually. And if you don't want it that bad, that's okay too. Just don't blame it all on bad instructors (even if they actually are poor instructors).
You can take it as a compliment. Though it may feel unfair and like you're not getting as much support from the instructors, they are in fact noticing you and giving you a chance to show and practice your fortitude, perserverance, problem-solving skills, humility etc. The goal isn't to get everything right, be complimented, and avoid being criticized; the goal is to adapt and learn from even difficult, uncomfortable, discouraging situations. Again, it may be like a coach who taunts the training athlete "that's the best you can do, huh? I thought you were better than that!" Some students have felt threatened with failure right up until graduation, and then surprisingly find their previously discouraging instructors telling them "You did it! You'll be a great nurse!"
Personally, I don't like this approach and wouldn't choose a mentor or coach who worked that way, but we may not have much choice in our instructors / preceptors / colleagues. Thinking of what feels like unsupportive criticism as at best well-intentioned harshness or at worst, practice dealing with a difficult person, makes me a bit more tolerant of it and able to work with it a bit. I still don't have to like it, though!