But if you got through some more rounds of education, then you might start to think. A professor that requires her students to buy a textbook she authored is something to think about.
What I found interesting in one of the degrees I got was that students did not even need the textbooks. The assignments and handouts were not tied to textbooks, though textbooks were certainly recommended and required as usual on the syllabi. So I decided not to buy any textbooks. I just used ones from the library. I learned more doing it this way than I ever did from mindlessly buying textbooks.
Still, the whole time I kept thinking, if every student tried this it would be unworkable. Professors did put materials, including texts, on reserve though, so "sharing" a copy of a text is not itself a crazy idea. Fortunately, few of my fellow students were keen to read the library's textbooks. As such, they were always readily available. I would routinely have about 7 texts checked out at any one time.
One of the things that kept the other students away from the library's textbook holdings was, I think, that they believed only the latest editions would be useful. Syllabi tell students to buy some specific edition of some textbook. And students, if they are fresh undergraduates, are very obedient. They will do as they are told.
But I found the dates on these texts mattered little. In some cases the best texts I found were "dated". But when you read lots of differenet texts, you get a much clearer picture of a subject area. And you can see the coverage as it has evolved. You can tell what's changed, and that itself is very useful knowledge. Now I'm absolutely hooked on this method of learning. I always seek out old texts as well as new ones.
The idea that "only the latest edition will work for this course" is another of the textbook publisher's little schemes. I'm sure they try to get faculty to use only the latest editions.
Interestingly, one can see the same dynamics played out in software. The hunger for the "new" thing, the bleeding edge, without any regard for history and how we got here. The obedience aspect is there too. To pick a random example, Microsoft tells people that they need Windows 8, and they obey. Little may have changed in 10-20-30-or-more years, the changes might be only cosmetic, but lots of people wouldn't know any different, because they focus only on what is considered "current". Like fresh undergraduates, they want to be told which edition to buy without ever thinking much about it.
The quantity of changes may be less relevant than the quality of the changes: i.e. did anything major change in this field in the last n number of years. With a closed source software program, like Windows, it's very difficult to assess the quality of the changes. All we see is the user interface.
It's like the syllabus that says you need the latest version of the textbook but does not tell you why the previous version will not do.
Look at it this way: in "most cases" (whether it's software or textbooks), from version to version, there's more substance that stays the same than substance which changes.
Not sure about you but I'm a little wary of buying the latest version of an expensive textbook in order to gain a small number of reatively minor changes that I could easily identify, and take note of, by comparing the latest version with the previous one.
When I took thermal physics waaay back in the 80s, my professor hated the newest edition of the text, and gave us all photocopies of the first edition.
The funny thing is that I was annoyed by this, falling firmly into the "undergradate mentality" you mention.