A difference so small that Microsoft initially intended to market Windows 11 as a new version of Windows 10. Other than those two massive, almost insurmountably significant errors, your reasoning was sound.
You're omitting the fact that earlier versions of Windows were more or less a one and done deal and not required massive continued development and updates modern Windows requires. Plus the much more numerous workforce Microsoft has on the payroll now versus back in those days on the Windows teams.
Your argument is factless and only based on the subjective opinion of "Windows 11 doesn't seem to different to me compared to Windows 10, so it can't cost too much to develop" which is silly and childish and shows your lack of understanding here.
That my friend is what we call a fact.
Just because you don't like being wrong doesn't mean you arent, and resorting to calling me childish for arguing with me reflects more on you than it does on me.
Looking at the data, in 1995 Microsoft charge consumers $210 for a retail copy of Windows 95. That's $434 in today's money adjusted for inflation. Windows XP Home retailed for $200 at launch, which is $356 in today's money. Meanwhile Windows 11 Home today retails for significantly cheaper at $140 for a product that's hugely more complex than Win 95 or Win XP were, while requiring way more staff and dev effort to build and support.
The finances just don't work out for me to see how the sale of a Windows 11 copy alone for $140 could make a profit at price given the 10 year lifecycle dev and support of a major Windows version.
I would guess a copy of Windows today would have to be sold for probably $500+ in order to be remotely profitable for Microsoft without ads or promotions, which no consumer would ever pay so I assume Microsoft is subsidizing it with ads/data collection or even taking a loss just to keep the retail price low to avoid loosing market share to Linux.