Eliezer writes in the theory of fun that to sell an idea to someone, you usually don't need to convince them it's a good thing to live with for their whole life. You only need to convince them that the first hour or day after they choose is going to be good.

I think that's a rational response, by the person you're trying to convince. The more distant the promised reward of whatever someone is touting to me, the more it will cost to reach it, and the more convinced I would have to be before taking it seriously enough to even begin. Or to put that the other way round, show me something that I can do right now and experience evidence that it works, and the bar for you to sell it to me is much lower.

"Jam tomorrow" is the promise of crooks and charlatans.