After a while, people will start to see the ever revolving door of the perpetual scam that is "This is the next Bitcoin! Trust me!"
You severely underestimate the ... sensibilities of people. Even if only 1% of the world will fall prey, that's still 75 million of them out there.
If a million of them get smart every year, we are looking at 20 block reward halvings before the population of unsensible people are depleted.