Realistically, the vast majority of people don't have a "few million" lying around that they can just casually risk on a huge gamble like this. It's likely you have at least several tens of millions but more likely hundreds of millions before the risk/reward would even come close to making sense (because you wouldn't want to commit most of your resources). The most plausible scenario is therefore something like a hedge fund.

You're reading "you" to mean the reader (highly implausible), I'm reading it as the generic/impersonal "you" (as in "one could spend...").

So sure, there are a tiny percentage of people who might consider doing this themselves and they don't need to worry about insider trading (although we're still pretty close to market manipulation where the sole purpose of the adverts is to crash the share price and profit from that). A much larger percentage of people who might consider such a thing would need to at least examine whether they might trigger insider trading laws.

Blanket statements don't work here.