They are sleep snobs, OP. They just don't understand anything but sleep between 11pm and 7am.
I remember my sil going on at great length about how disgustingly lazy it was to sleep during the day when I worked nights.
Some people are very dim indeed and unable to realise that other people are not them. These are also often the people who will consider, say, an otherwise-fluent Norwegian very thick for not being familiar with a particularly long and unusual word in English (maybe their 3rd or 4th language), but if you challenge them to say any very simple statement in Norwegian, they'd look at you like you were mad: "But I'm not Norwegian!"
Even for people who don't work nights, I've never understood why night owls are considered lazy and larks virtuous. Surely, it's what you do with your time that makes the difference, whether you do something at 6am after rising early or at 2am before going to bed - what does it matter, as long as it fits in well with your family and work?
They'll happily call you lazy for not getting up until, say 10am, on a non-working day, but if you in return call them lazy for going to bed at 10pm, they'll take the greatest offence, because "That's bedtime, duh!"
I used to work a normal daytime job and did 9-5, whereas others did 8-4. Same hours, slightly staggered, no big deal, you'd think. Except they didn't half think themselves superior. "Good morning, I've already been here an hour!" Congratulations - and you'll go home an hour earlier too. This department has to be covered between 9-5, so if I didn't willingly do it, you'd have to; being allowed to start and finish an hour earlier than the core operating times is a concession that the bosses make for you. And aside from all this, on the odd occasion when I had cause to get there early myself, it became evident that they spent most of that earlier hour chatting (probably about how virtuous they were) and eating breakfast, whilst I got in for 9 and was straight to work, as the emails started coming in. They were still coming in and being dealt with by me once they'd gone home at 4.
With some people, the fact that they rise very early is the only thing they have to boast about, which is so sad and pathetic - like boasting that you have a blue front door or prefer leek to cabbage. They'll randomly ask when you got up, just so they can then reply "Oooooh, I'd been up three hours already by then!" That's nice for you, dear - do you want a medal like Muttley? In contrast, I have a friend who gets up at 5:30 every morning, as he enjoys an early morning walk. he doesn't go around telling everybody about it, nor does he judge people who rise later, because he's a reasonable person who understands that people live their lives differently. I couldn't imagine being up for 5:30 every morning, but I am not him, so judgement and criticism are most definitely not forthcoming from me.