Temptation will kill so many holders that have a long ter mindset, we are ahead of so many lucrative bubbles that statistically, most (and I hope im not one of them) will sell way to early, when we think we sold at the top.
Nothing wrong with taking out an amount that feels satisfying at the time. Life is short. Waiting around until you're 75 to max your gains is the wrong move.
I guess the best thing is settle that figure in your mind, keep back a certain amount of coinage back just in case and take the plunge at the right moment.