1. They believe the price will drop and want to sell before that happens. If this is the case, it raises the question why they think the company is overpriced since, as somebody involved with the company for a long time, they might have insights the public missed.
2. They want to cash out for reasons unrelated to the company. For example because their investment model is to invest in a private company, wait until it goes public, and then sell.
[0]:https://twitter.com/nntaleb/status/1383860897999851521?s=19
Compared this, from the quoted tweet:
> On the same day #Coinbase CEO @brian_armstrong was on @CNBC publicly pumping COIN, he was privately dumping 71% of his shares.
with [1]:
> CEO Brian Armstrong sold 749,999 shares in three batches at prices ranging from $381 to $410.40 per for total proceeds of $291.8 million, according to one filing. While a Coinbase representative declined to comment due to the company being in a so-called “quiet period,” based on filings made before the listing, it would indicate Armstrong sold about 1.5% of his stake.
[EDIT: I'll note that both Taleb and the person he quoted have had their mistake pointed out to them and have just ignored it, which frankly is a pretty awful look]
[1] https://finance.yahoo.com/news/coinbase-ceo-sold-291-8m-2350...
The case in point is USV selling all their stake in a company and what that means for the business.
I didn't say anything about the CEO