I think this probably depends on how active your lifestyle is. With my current lifestyle, I usually get at least a good 6000-8000 steps just by living my life normally, and often I get more steps in than that.
If I didn't take a single step during a day and then tried to make up 10000 steps, that'd be a bit under two hours, at my usual pace of ~6000 steps an hour.
Yea, also many people don't realise how many steps they are doing. I don't do many steps at work and when I use my car to get to work then I probably get only 1-2k steps, when I just relax at home after work. So I try to take walk during my breaks and use my bike to get to work. Just little things like that are already a big improvments.
As far as I've understood it, the current research on steps per day in relation to longevity tries to map it towards the likelyhood of it naturally achieving the guideline of 150 minutes of moderate exercise - would you really be able to get 150 minutes of moderate exercise while only walking 4k steps a day?
I read a german article which says 4-5k steps is already a good improvment to reduce risk of high blood pressure or heart diseases. Yes, ofc it's better to do more movement but many people barely do 1-3k steps a day. 10k steps just sounds so hard to achieve for many people which is why it's not really a good advice.