How do you continue holding a stock that's gone up a lot?

I find it easier to hold a losing stock than a winning one. Like if one of my positions drops 50% I have no problems holding it for years waiting, hoping for it to recover. It's like I refuse to sell it out of stubbornness, but when it comes to my winning stocks, I start getting anxious and jittery because I don't want to lose the unrealised gains I've made. Once one of my positions goes above 100%, I really start getting twitchy, even if the company is fundamentally crushing it and doing really well financially. I hate the feeling of thinking "if it drops I'll be back to where I started, and maybe it'll even go lower than my entry" so it compels me to sell to lock in that profit. Which is fine, if I was going to use that money to buy a car or a deposit for a house or something tangible. But all I end up doing is selling to buy some other stock. And by doing that I'm essentially saying "this new stock will perform better than the one I currently hold" but there's often no justification for that, except that the chart of the company I move my money to has a less "all time parabolic high" looking chart. I know the old saying of "if I had money to buy the company today, would I buy it?" and if the answer is yes, then don't sell. But when I see a chart that looks like a hockey stick, it makes me really nervous that "this can't continue it's going to be shorted into the ground everyone is going to take profits soon". There are people here who have the stones to hold a stock for 700%, 900%, 1200% or more. Like how the hell do you do it? And then there's people who even ADD more to their positions on top of the bull run. Like I saw a post of someone who was up 450% on rocket lab and had about 400 shares, then they added another 600 shares. So they even doubled their position on the top of a 450% run... Which was the right call because they're up like 1000% now.