I’ve come up with a great analogy for why Anakin’s turn doesn’t work.
Imagine you have a romantic partner and they get into a terrible car accident. You’ve been in the hospital for 3 days and there’s a possibility she may die. You’re worried sick and have barely slept. Satan himself (for the record, I’m an atheist, but this is hypothetical) appears to you and says, “I’ll save her if you kill all of your neighbors, coworkers and their families, every friend you’ve ever had and their families, your entire extended family, and your partner’s entire extended family. This includes any of the children or babies.”
Who would do that?
Like, pact with the devil stories exist, but that’s just way too far. If he just showed up and said, “I’m gonna save your partner in exchange for your soul”, then sure, I can see someone doing that, even if it’s still not smart. But murdering everyone that you know for a deal that you don’t even know for certain whether they can or will actually do it, someone you know is evil and a liar? It’s just beyond stupid.
The only way it works is if Anakin has tangible evidence that there is a dark side power to cheat death and the knowledge exists to learn. Anakin should become evil, but not be stupid to agree to a bargain when he has nothing to go on except a story.