2000s: The textbook costs $100, but it was written by one of the absolutely most respected people in the field. People keep their copies forever and continue to refer back to it throughout their careers. It's worth getting the second edition which incorporates decades of small fixes to the original, but the first edition is fine too.

2026: The textbook costs $660 with required online learning access code. It was written by fake people under the command of a giant corporation. You have to the get the 32nd edition or you'll fail all of your exams because everything completely changes each year. The book reads like it was written by toddler and it's full of pointless garbage that just insults your intelligence. The online learning is even worse. You'd sell it as soon as you could except it is completely worthless the instant you bought it.