Besides, why would it matter if the scientists were wrong? Being wrong might be rational if your belief is based on the best available evidence. Changing your mind doesn't mean you past belief was stupid or a lie. This is how science works. We all should have learned this in middle school.
A version of overpopulation is still very much a concern. Obviously, most kinds of environmental destruction scale with population. Our current farming practices have managed to keep people fed, but only by draining aquifers and polluting waterways. Our current modes of transportation have managed to transport billions of people, but only by pumping out destructive amounts of carbon.
Overpopulation is not, in itself, the problem. We know how to sustainably support a population much larger than the one that exists today. However, a large population is a multiplier to the destruction of all our unsustainable practices.