"Billionaires are literally cancer" is false specifically because "literally" does not mean "figuratively".
Correct. But that is not what OP said. Read it again and I think you will see that OP is saying that "Billionaires are cancer" is not a figurative statement at all, but a literal one. You can disagree with them (I do, btw), but they have not misused the word "literally."
"Billionaires are literally cancer" is simply a false statement, unless "literally" was used, incorrectly, as hyperbole.
That is my point. Literally can be used correctly in a statement that is not correct, and my reading of the original post is that was OP's intention. They did not misuse the word "literally."
Edit to add:
OP says cancer can be used literally to refer to billionaires, you say it cannot. One of you must be wrong, but neither is misusing the word "literally."
Then you do not understand what the word "literally" literally means.
Oooo, sick burn!! I don't know if I'll recover from that!
My point is that I believe OP was using the word "literally" to mean what it literally means, and not just using it for emphasis as it is so often used these days. They may still be wrong, but they did not misuse the word.
I think OP used literally correctly here. They are saying that one possible definition of the word cancer can include billionaires as an instance. That's not the definition you'll find in any dictionary, but those lag behind the true language as it evolves.
People think they understand numbers like billion because they understand thousand and billion is just thousand times thousand (million) times thousand. Multiplication is fairly intuitive, but exponentiation is not. Without explicitly thinking it through people feel like 1000^3 is not very different from 1000 * 3.
I identify strongly with the frustration in this sentiment.
But you do realise the US is the foremost nuclear power in the world? Right?
That's why the world should have done anything and everything possible to keep US from falling into fascist hands. But now it's too late.