That Ehrlich made a bundle on wrong predictions isn’t such a big deal — we’ve had dozens of doomsaying futurists who’ve cashed in on fears that never materialized.
The problem is people listened to him.
Across the world, governments adopted population-trimming policies, from massively subsidized birth control to promoting two-worker households to China’s draconian “one child” policy, in which each couple was allowed only one child.
That has left China with crippling demographic problems just as it hopes to burst forth as a superpower on the global scene; it’s now trying to encourage people to have more babies, as its leadership realizes it’s hard to be a superpower when your military-age population is shrinking (and, as only children, too valued by their parents to safely be employed as cannon fodder), your elderly population is growing and your society is stagnating.