You're not alone, it happens to everyone, here's something I tried and it worked out for me. I don't buybaok my coins at once and neither do I sell all my allocation am the same time too. I sell them gradually or I buy gradually. When I do this, it doesn't matter how the market wants to play her game, I'll still benefit. If the prices dump after buying that's fine I have spare funds to buy more.
Same thing if he price rises after I sell, I have some coins left that I can sell in the future. The market always plays this trick on everyone but you have to make out a way so the market doesn't make a fool of you always, you can just hold and avoid all this and when you're in profit you leave the market totally.