Well, a theft can be voluntary: that’s what con-artists do all the time!

Now that you've reached the point of calling everything theft, there is nowhere to go. Congratulations.

Well according to Matt Levine, everything is securities fraud...

Con artists are getting your consent via deception. Is this the case what derivative traders are doing?

Well, one could argue that they are just smarter than other people and manage to find market opportunities. Good for them I guess. But technically since it’s mostly a zero-sum game would it be wrong to consider that they use their smarts to deprive other people of value?

Do you really need me to explain why fraud is wrong? Fraud is wrong because you're betraying someone's trust. It's bad for society because it adds friction to business dealings. When you can't trust your counterparty, you have to expend tons of money doing due diligence. This is true regardless if you're smart or not. Being the smartest person in the world isn't going to help you if you're being deceived (assuming you're not omnipresent).

*Omniscient

Though I guess it might be hard to deceive an entity that is literally everywhere.

This is also the case I make against bitcoin re: the value of trust.

That’s called fraud, otherwise known as theft by deception. Trading is transparent, people know all the details upfront and are not being deceived.