I'm going to waste the time of someone who is trying to get me to join a pyramid scheme
Why is it important to you to waste this persons time?
He is, first off, trying to sell me an idea that doesn't interest me at all.
I can understand that you are not interested in buying anything. There is no need to be rude by wasting someone's time intentionally.
He's also a scammer.
That may be true, but wasting his time won't prevent him from scamming others, which is what you should want.