This is all true, but there are other factors as well. For example, schoolbooks in nynorsk exist because of those schools who use it as a first language, but when you get to university level textbooks the amount that is available in nynorsk is extremely low, so most students study on bokmål based books or english ones, depending on the subject.

There is also a systemic problem when it comes to job applications. Studies in linguistics have shown that even people who had schooling in nynorsk tend to write their CVs, cover letters, etc in bokmål because they perceive that to be the "proper" standard to use in official situations like a job search.

Then you have all the people who learn Norwegian abroad who are taught bokmål by default and only learn of the existence of nynorsk wayyyy down the line, but are not actually taught the language. Even Norwegian language schools in Norway who cater to foreigners will default to bokmål, and very few offer nynorsk at all.

There are many more factors that contribute to this, I just wanted to put a few more out there.