This has been one of the majority problem in the trading space today most average traders who already have average experience on trading mostly have this state of fears in them, In the trading space many average trader have this fear of succeeding, this mostly happens to an average traders or business owners which they likely say, "what if one red trade takes it all alway" they suddenly become more anxious having that fear that they might start all over again.
A trader that knows his craft won't be afraid of succeeding but might get scared of failing because he isn't in control of the failure but for the success, he has everything in his hands but there could be times when things don't go as he plans although that won't matter much to him since that'll only be a small percentage of his overall trade history. Losing one trade out of 10 trades isn't a bad outcome but only proves you aren't perfect and allowed to make some mistakes.
Don't start trading without learning the basics things needed and you won't be scared of success. I'm still learning and haven't become perfect at trading but I have never been scared of succeeding instead get overjoy sometimes, thinking that the trades that I opened are going to make me my biggest money but I get disappointed when I don't get the kind of money that I was expecting because of my impatience.