For the company. Not really though that gets more philosophical. Classically a company would get money during the initial public offering (and anything leading up to it) and that is the end of that, some have since gone on to issue more but that tends to be seen as diluting what is out there and not that good. Some also buy back shares which is also contentious.
As well as the selling before bad news hits thing mentioned in the other post he might never have actually bought shares. Instead he might well have bought an options contract (have not seen the facts of this case but it is the traditional way this is done as far easier to get into and far more profit potential) which means it is the market maker/one he bought the contracts from that lost out instead.
Some more, some less is fine if you are using public information -- you can be a line goes up, line goes down type of trader if you want, you can be a degenerate gambler if you like, or you can watch the consumer sentiment, debt levels (company, consumer, national, regional... the lot), natural disasters, reviews of product, reviews of competitor products, reviews of off the wall competitors (horse and buggy business and suddenly there is cars sort of thing), satellite imagery of their car parks (
https://www.theatlantic.com/magazine/archive/2019/05/stock-value-satellite-images-investing/586009/ ), have robots read the news to guess price movements (CEO fraud embezzlement, class action... all negative and likely to move stock price down) and so on and so on for the markets the company in an attempt to do better than the others at guessing future moves. All these are considered perfectly normal behaviour. The trouble for insider trading (using information you came by say during the course of your employment that nobody else outside the company knows and is likely to change how the company is perceived) comes in that if it is allowed it will very quickly devolve into only those that have the insider information get to play in the market else they just lose, various investment firms go bankrupt (which means nobody retires), no money gets circulated around the economy beyond what has to be for simple transactions and that is all very bad news for your advanced economy. Or if you prefer then there is a reason it is treated up there with making counterfeit currency and rich and powerful people get nailed for it where they skate on all manner of other nastiness.