Do you think there's more or less than a 1 in a million chance of someone reading and executing one of these ideas?

Vastly less. I expect the chances of a given person genuinely wanting to indiscriminately harm humanity -- not just as an idle revenge fantasy or as a means of signaling cynicism, but as a goal motivating actual behavior even when it comes at high costs -- to be somewhere in the neighborhood of one in a million already, if not lower. The chance of such a person reading the offending post, following the reasoning, deciding to implement it, and coming up with the liquid money to fund it (million-dollar budgets don't grow on trees) is very small indeed.

It's much easier to find people that want to direct harm at some nation or identity group, but most of the ideas in this thread aren't so easily targeted.