It's a little silly of a question, to be honest. Back then, it's all we knew and had. Sure there were cartridges for consoles, etc that were instant, but those weren't copyable, and even when playing a game you saw this keyboard and knew you were doing computer-stuff with it, unlike having just a joystick plugged into a 2600. Though, sure, there were hard drives, and some games would install to them, but in general it was a floppy based system. It's also the case that you'd then appreciate things like the loading screen art or the occasional music or something that would keep you mildly amused while you sat there (conversely, very annoyed when programmers didn't use a 2nd drive, bad swapping, etc).
Also, if you went to the Amiga from the C64 (or something with similar, excruciating load times) the Amiga's floppies were incredibly fast.
I think the question would be like, in 20 years, wondering how people could have got along staring at a monitor all the time, when people in 2029 put on VR glasses.