Things like this could be a little misleading because the "missed opportunity" was not the fact that this person sold his coins at whatever price, the actual missed opportunity is when you sell but never buy back in either the dip or when you figure you made a mistake and price goes higher.
Now all he have is ethereum and few other altcoins and not bitcoins.
In other words he is still an idiot since he is baghlding shitcoins. It is true that some people never change which is why we always see only a small number of successful people while the rest are chasing their own tail.