Win11's RAM usage is maybe 10% more than Win10's, there's barely any difference. I'm not sure what your point is here. The choice for most people who want to stay on Windows is an unsupported OS versus a supported one (in terms of security updates).
Yes. Their aging hardware which has approx 10X the performance they need for daily tasks, is supported by Win10, or Win8 or 7, whatever, but not Win11 (as far as they know) and the increasing cost of hardware will delay them buying whole new (OEM) systems to run Win11 until their current system breaks and costs more to repair than it's worth - but with rising new system costs, the break even point for repairing rises too.
Security updates are mostly a myth for home users behind a router, using secure wifi or ethernet, and
running a modern browser. Consider an analogy. There's been a rash of ATM thefts from convenient stores recently, and they need to update their security if they want to prevent that - but I have no ATM and do not need a security update against that vulnerability. This has been true for windows home users, for people security conscious to the point of not just muttering "security" but actually practicing it, ever since Windows UAC and firewall.
I probably ask in various forums at least twice every year for the past decade, if anyone can name a single Windows SEVEN vulnerability that the many Win7 boxes I've had online (behind a router, this isn't the dial-up era) 24/7 for years, are vulnerable to, in the extremely common home use scenarios I have. None of t hem have ever been exploited. "Vulnerable" means actually vulnerable to, just like you're not actually vulnerable to an ATM theft if you don't
have an ATM. Many people savvy enough to think much about it, are more vulnerable to problems the updates themselves cause, than whatever problem the update was supposed to solve, with "update" being used interchangably with new Windows "OS version".
This is an edge case example today, I wouldn't advise to put Win7 on a new hardware build even if drivers were available, because modern browser support is running out and most people on their single main-use PC, are going to want modern browser support for years into the future - but Win10 does have that covered. I would not advise that anyone switch to Win11 unless building a new PC with a specific need for 11, or buying OEM and that kludge of an OS just came on it.