Surely, if there was a completely legal way to inflict great harm on humanity for only $1Million then there are a ton of people/groups with the desire and resources to do those things.
Are you sure? Who? The people who do inflict great harm on humanity aren't cartoon monsters. They're commonly either unethically selfish, foolishly utopian, or terroristic. The selfish ones will only care about an idea for doing harm if the harm is a byproduct of an idea for getting something they want. The utopians don't try to do harm, they just create unintended consequences when trying to do good. Neither kind of person is going to be at all interested in an idea whose sole purpose is to do great harm.
Even terrorism is typically either a negotiating point for demands, a provocation to overreaction, or at worst a pure act of revenge; here they actually have a desire to do harm, but targeted harm, not generic "harm on humanity". Unless an efficient act of anti-altruism happens to affect only a subset of humanity that's contained within a set of terrorist targets, it's not even going to interest them!
Edit: The purpose of this question is not to make the world worse, but to see whether we actually have concrete ideas of what would, and my guess is that most of us don't, not in a really concrete way. From the downvotes I'm wondering if everyone else is thinking way darker directions than I am. If so please share.
There is a lot of discussion here about effective altruism. Organizations like GiveWell with donations, using criterion like quality-life-years-saved-per-dollar. People distinguish warm-and-fuzzy giving from the most effective use of dollars from various utilitarian perspectives.
But I want to ask a different question: What would effective anti-altruism be?
To make it more concrete:
I am an eccentric multimillionaire, proposing a contest to all of you, who will for the purposes of this exercise play greedy and callous, yet honest and efficient, contest entrants.
Whoever can propose the most negative possible use for my money, in the sense that it causes the greatest amount of global misery, (feel free to argue for your own interpretation of the details of what this means) will receive $1 million to carry out his or her proposal and $1 million to keep for him or herself to with as desired.
A few rules:
1) Everything must be 100% legal in whatever jurisdiction you propose. Edit: People had trouble with the old phrasing, so I'll add that it should not only be legal in the letter of the law, but also in some reasonable interpretation of the spirit of the law.
1a) In fact, I encourage you to think of things that aren't merely legal but that would also be legal under whatever your favorite hypothetical laws are. Maybe that means non-coercive, non-violent, or something else in that vein.
2) This money may be used as seed funding for a non-profit or for-profit anti-altruistic venture, but I will take into account both the risk and the marginal impact of only the first million dollars.
3) Risk and plausibility are factors just as they would be in any investment for effective altruism
4) If you're going to propose that you keep and embezzle the first million dollars, you should have an extremely good justification for why such a mundane plan would match my standards for anti-altruism.
I hope this pushes you all to think of truly anti-altruistic means of spending this money. I think you may find that effective anti-altruism is a good deal harder than you'd believe.