The stock market is 100% optional to participate in, and every broker tells you (is legally required to tell you, in fact) that you should go in with the expectation that you're going to lose money. That didn't stop whatever forces have made them essentially required to plan for the normal life stage of retirement these days.
Betting against something that looks like an insider making the bet really is something willingly done. It's just a dumb bet.
Absolutely garbage take, to be quite honest with you. War profiteering is one of the most heinous crimes imaginable, and the last thing we need in this world is more opportunities for it. Regardless of whether the punters getting screwed consented to gambling or not, the problem is the perverse incentives it creates at the highest echelons of power. Abusing access to military intel for profit is foul behavior that will only degrade the quality of our governance and foreign policy, not to mention the literal lives that will be lost as a result.