Riding with fear causes a block. The horse feels a rider's fear. Our communications with our horse come via our body. Fear causes tightness that will invite a horse to do something, often other than what we intend. So, fear in a rider can confuse a horse in the mildest sense, and frighten a horse in the worst sense.
Fear is natural.
There are many other forms of fear that can stem from the simple, natural fear of loss of control, uncertainty of the unknown, of our balance, to extreme fear of being hurt. Yes, and some fear is very useful to protect ourselves from making dangerous errors in judgment. Guilt often comes from false expectations from others or ourselves. It can also come from our pride. I don't think any rider should be afraid of admitting fear.