Yes, two seconds and more can absolutely be network latency. If you don't think this is possible nor a regular occurrence for many people, you have been living in a bubble.
Not at all contesting this.
> a regular occurrence for many people
Maybe I am living in a bubble, but this seems unlikely unless your definition of "many" is fairly liberal.
On a 2G connection you might get up to 1000ms latency, if you're in a remote part of the world could could add an extra 500ms or more due to geography. DNS lookup, TLS handshake, and the data transfer, you could potentially get up to 3+ seconds adding it all up. But—apart from aspects of that being one-off, as I mentioned above—generally speaking the whole lot is an example of an extreme. Your average user really shouldn't be seeing that.
If the latter, where are you getting 15-10 second figures from?
In a world with more than 7 billion human beings and a large percentage of them being users of the internet, it doesn’t matter if we are talking about 1% or even only 0.01% of users. Any percentage will include many people.
It might only be many actual users if you’re Google or Facebook, though.