Gather around and sit at my feet and I shall tell you a tale of both sadness and joy.
The year was the good old days of 2016. Our president was the president at the time. There was once a man, a good man. He kept putting half his take home pay into TSLA, only to see it being chipped away week after week from a dropping SP. There was no solace for that man, all he knew was despair, but he kept soldiering on, knowing TSLA will do well one day. Suddenly, around the end of the year, TSLA jumped. Then jumped again, and again, and yet again. "What is this witchcraft?", he thought. This is too unnatural, this has jumped too much, it's wiser to sell now. So, he sold, expecting TSLA to fall and correct itself. Except, he was wrong. It kept jumping. Another 10 points, another 20 points, and beyond.
"This is absolutely nuts. Should I buy back in now, knowing that the price is unnaturally high?" Eventually, he broke down and bought back in, knowing the gains he had lost from selling early. To his good fortune, it kept climbing higher and higher. However, once again, he was getting cold feet. "This is getting stupid now. For months, it's gone up in a straight line for seemingly no reason!". Once again, he sold, and once again, he fell into despair, seeing the SP climb higher and higher.
Then he bought in again, then the price crashed. Once again, despair.
Some time later, he sold due to needing to transfer money around and the price dropped around 50 points, which made him happy when he bought back in.
Moral of the story is to be very care when jumping in and out like that.