People don't like changes (in computer stuff)
There are always some people who like to fiddle around with things. Some number of photographers are always shuffling camera settings or experimenting with different post-processing; some number of cyclists are always changing bits of their bikes; some car enthusiasts like fiddling with engines and so on. But most people are not really interested in this; they want to get something that works and then they want it to keep on just like that, because it works and it's what they know.
Computers are not an exception to this. For most people, a computer is merely a tool, like their car. What this means is that people don't like their computers to change, any more than they want other things in their life to change. Imagine how it would be if every time you took your car in for service, the mechanics changed something about how the dashboard and controls worked, and every few years during a big service call they would replace the dashboard entirely with a new one that maybe mostly looked and worked the same. Or not. You and many other people would find it infuriating, and pretty soon people would stop bringing their cars in for anything except essential service.
Unfortunately us computer people really love to change things in updates, and of course 'upgrade' is generally synonymous with 'changes' in practice. Against all available evidence we are convinced that people want the latest shiny things we come up with, so we have a terrible track record of forcing them down people's throats. This is not what people want. People want stuff to work, and once it works they want us to stop screwing with it because it works, thanks. People are well aware that us screwing with stuff could perhaps improve it, but that's what everyone claims about all changes; rarely do people push out a change that says 'we're making your life worse' and most changes are created with the belief that they're either necessary or an improvement. However, much of the time the changes don't particularly make people's lives clearly better, and when they do make people's lives better in the long run there is often a significant payoff period that makes the disruption not worth it in the short run.
(Rare and precious is a non-bugfix update that immediately makes people's lives better. And bugfix updates are just making things work the way they should have in the first place.)
In my opinion, this is a fundamental reason why forcing updates on people is not particularly a good answer to people not patching. Unless upgrades and updates magically stop changing things, forcing updates means forcing changes, which makes people unhappy because they generally very much do not want that.
(There is also the chance that an update will do harm. Every time that happens, people's trust in updates decays along with their willingness to take the risk. If your system works now, applying an update might keep it working or it might blow things up, so applying an update is always a risk.)