After exponential population growth like humans are experiencing, population biologists have demonstrated that some populations go extinct, and some populations stabilize on a sickening bouncy curve in which numbers exceed the carrying capacity of the environment and then die off...regrow...exceed...die off...regrow...
Our exploitation of environmental limits has been so extreme I agree with you. There will likely be a massive collapse due to disease, shortage of nutrients, elimination of sustaining ecosystems, etc. There's lots of practical observations to be made that predict this model. Some people like to consider this from a "cosmic" perspective, and that is comforting, because the human reality of such a collapse will be incomprehensible.
However, there's no reason not to give real weight to the incomprehensibility of that sickening bouncy curve, too, should we end up there. There's nothing good about its famines, its desperations, its sufferings. Repetitive population crashes aren't a happy alternative.
The sad thing is, we are gifted with the intelligence to make decisions about our population growth, our effect on the future of other species, and our ability to live richly beneath the environmental limits of the Earth. But we choose to multiply instead for our own short-sighted, selfish purposes.