The point of the dilemma about Vision’s life was not to ultimately answer “Yes, turns out, one life IS worth trillions, who knew?”

The point is to show us how that decision changes when there’s a third option.

They don’t want to murder an innocent person because he happens to exist in the wrong way. They don’t want to make another innocent person murder him. And they don’t have to! They can extract the Mind Stone, have Wanda destroy it, and be True Heroes All Along. They can be noble, heroic, and be satisfied they did the morally correct thing.

You know, like Thanos’ people tried to do.

And that’s the point. The parallel between two situations in taking a third way out that means not having to commit a terrible act until it’s too late.

But there’s a catch here–Thanos has the power of inevitability on his side. He has the Time Stone. It wouldn’t have mattered if Wanda had or hadn’t. Whether Wanda did it earlier or later.

And that’s the thing, Thanos’ plan is short sighted. People will continue to populate, resources will continue to dwindle. That’s inevitable too.

So now or later, here or there, “destiny arrives”. Thanos is only delaying it—and he plays a cold numbers game to do so.

What separates him from the heroes isn’t that heroes aren’t willing to. Quill and Wanda both try. It’s that they’re willing to try something else first. Because destiny is always going to arrive one way or another—but they’re going to fight for something better.