All the Windows OS's have 10 year support. Windows 10 is no different.
Windows 7 launched in October 2009 and supports ends 10 years later in Jan 2020.
But that's not what people are so irate about. It's not "how long a Windows version is going to be supported." Most people couldn't care less. The issue is, how long can I keep my PC running usefully, without some outsider forcing me to buy a new one.
In the past, we could buy a Windows upgrade, and make it work. PC performance improvements have leveled off, since the days of 64-bit CPUs. If a 64-bit PC can run Windows 2000 well, it can also run Windows 10 well.
My wife's PC is a 2nd gen Intel Core i5, bought with Windows 7 pre-installed. It's running Windows 10 perfectly fine. It should continue doing so, barring hardware failure, at least until 2025. Windows 10 was supposed to be updated indefinitely, until suddenly Microsoft got this new religion.
Now they put a hard limit on the max lifespan of our PCs. Very much Apple-like. It's the reason many of us steer clear of any Apple product. If their excuse is hardware level security features this time around, and even fail PCs which meet all those requirements anyway, next time they'll dream up some other "trust us, it's for your own good" excuses.