There are resources. For the last while, we’ve had the ability to take care of pretty much everyone, if only the resources were distributed fairly evenly. This would mean that Americans (in particular) would have to give up some of their cars and lattes, though, and that would be too much of a hardship. (Let’s forget for a while that to an African living on $200 a year, it doesn’t look like much of a hardship.)
On the other hand, there are only so many resources. We seem to be speeding through oil in particular, and also natural gas. In the past, when a society ran out of wood, they either collapsed or found an alternative like coal for their energy needs. People seem to think that when we run down on oil, we’ll just pop back up with something like solar or nuclear power. In this case, though, oil is particularly special because it is not only fuel, but food. We have a big population in part because oil made food cheap and plentiful. When oil becomes scarce and/or too expensive, we can expect the next Malthusian catastrophe.
So, do we have too many people? It depends upon the carrying capacity of our resources and the quality of things like water and air. Even with a lower population, too few resources for that population can still mean bad things. If and when there are more people than can be supported by this planet, it will correct itself. I hope it’s not as painful as I believe it will be.