In a retirement account as well.

This could only be done in a retirement account.

If someone sold at $528, with a basis of $30 or so, that would be a $498 long-term capital gain. And they would have to pay 23.8% in capital gains taxes, which comes to $118.50. Buying back at $478 means that with the money remaining after taxes, they could only buy back around 80% of the shares they had sold. And that means that as the stock rises over the next few decades, they only benefit with about 80% of the gains that they would have had had they not sold any of the shares (at $528).

But since I do like to "play" sometimes, I use options periodically. I sell puts on a regular basis at strike prices where I would surely buy if I had the chance. Unfortunately (or fortunately as the case may be), all my sold puts have expired worthless except for the 305 strike price puts that I sold a couple of years ago, those were exercised and assigned to me, so I do have some shares with just under a $300 basis.