In the very beginning of computers. The computer guy said. Make pictures smaller.
Not trying to sound old or something, but i do remeber those times! Screen resolution 1024x768 considered high and wasn't available for a lot of PC users in the mid 90's. 800x600 was "more than enough". There was a lot of pioneering digital cameras, whose goal was to reach the Holy Grail of a consumer digital imaging - a megapixel. Yep, just the one megapixel!
Time cut to a first half of 00's, when internet access for the most people was not that broadband and inexpensive as now. The "good form" for a blogging was to put a thumbnails around 200x150 px or even less with a clickable link to a 600x400 "full size image". That is what i actually did in my early days on LiveJournal. If your post has a "cut" - you should warn your viewers with something like "Achtung, traffic! There is a 10 photos of 967 kb of total size under the cut!".
Now we open a 100+ megabytes web page from our smartphone and don't even flinch. Odds are there a little to none photos or videos on the said web page, just a some short text.
I've used the Canon EOS 300D ("the first affordable DSLR camera in the world") from 2004 to a 2008. It has 6 megapixels - "why do you need that much, you showoff!". Now the full size photo from that camera has the less pixel count than a common 4k display. It has black bars all around your photo, when you view EOS 300D images in full size on 4k display (you can see it in the attached screenshot). In that very moment i have actually felt, how far the tech did go over those years.
Oh, you did send me down the memory lane!
Skorohod might be willing to sell pictures with more pixels.
Skorohod, the notorious pixel peddler
But seriously, though: Dzen natively provides a 2400 px images on the longer side, and with a minimum DPI of 100 you could print out a 60x40 cm poster. Just don't look very close at the result
And if you still be in need of the picture of higher resolution - i can provide it for free. I'm always trying keep my hobbies as far from commercialising as possible.