I wouldn't generally want things like pizza for breakfast but I'll eat it as such if it's around (leftovers etc).
A lot of this is simply cultural. I once has soup for breakfast at my partner's parents' and her mum thought it was weird!
RE some people not wanting to eat in the morning: most (younger) people tend to have a natural sleep cycle which is quite late (i.e. naturally fall asleep in the early morning and naturally wake up 9-12). If you have that and force yourself awake early for social or more likely work/education reasons the your body just hasn't caught up and of course your appetite won't be there yet. I'd bet if you were just left to wake up when ever your body felt like it you'd be hungry quite quickly afterwards.
For the sake of adding to the group:
I tend to have things like yoghurt and fruit (and sometimes something like oats), bacon rolls, cooked breakfast (eggs, bacon, beans,maybe some sausages), toast and soup etc for breakfast.