People who invest in only a few stocks and go all in, how to you manage risk?

I moved on from ETFs and am doing individual stocks. I’ve been doing decent w the bull run but I’m holding I believe 35 stocks as of writing this. Some are doing better than others. Well I sometimes see posts from time to time of people starting w 100k and making bank off having under 10 holdings in their portfolio. Like massive run up gains w certain picks. Is this a gradual skill level up whereas time goes on and you get more comfortable you go “all in” on a select number of stocks? One of my