I am not angry because I got rejected once, I am angry because there is for me no guarantee that I will ever not be rejected. If it was one woman that does the rejecting nobody here would care, rejection is in these cases a normal part of life, but when all you get are rejections you have a reason to care/be frustrated.
That we won't get Stacies (e.g. conventionally attractive/neurotypical women) is clear for every -cel with a hince of situational awareness out there (most of the time even before entering puberty or at least in the earliest months of it), most of us don't even want them - why when we neither share their hobbies nor anything with them? The reason why we are angry isn't Chad/Stacy, it's that an ugly/disabled/autistic/fat woman would not fuck an ugly/disabled/autistic/fat man. Our looksmatch doesn't want anything to do with us.
An analogy: If you get one rejection from a job interview it is not a problem, well, you didn't get your dream job - like almost all humans out there in the present, in the future and in the past, but you can still try again at a different place, making compromises is a necessity, perfect employment will for most people never exist, so why bother about a single lost opportunity. But when you only get rejections and therefore your livelihood is in danger you have a reason to care/be angry. When not even the shadiest/dirtiest burger shack wants to employ you as a janitor it's incredibly over for you.
We have realistic expectations, we aren't like high school drop-outs that try to work as a neurosurgeon/AI developer, we aren't ugly cripples looking for an able-bodied model-tier wife, we try to find what should be available to us considering our qualifications/stand in life and see that we don't get there.