A lot of the problem is that originally the developers of Python made it absurdly difficult to transition from Python 2 to Python 3, and thus the costs far exce

A lot of the problem is that originally the developers of Python made it absurdly difficult to transition from Python 2 to Python 3, and thus the costs far exceeded the benefits. It was historically difficult to write code that ran in both Python 2 and Python 3. If you wanted to transition to Python 3, you had to simultaneously transition every file in your program, every library you depended on, and all libraries they depended on transitively, to Python 3. The "2to3" program was supposed to automate, but this never worked reliably, and cannot work reliably - to do that reliably requires type information that is typically unavailable in Python. Things have gotten much better, thankfully. Python 3 (and 2) have been tweaked over the years to make it much easier to write code that will work on both Python 2 and 3, and to make it easier to tweak existing code so that it will work on both. As a result, it's possible to transition code a file at a time, or even a portion at a time, instead of the impossible "all at once" transition. Almost no one used Python 3 after it was released, or for a number of years later. Now that the developers of Python have started to make transition practical, people have started transitioning. Still, it takes real effort to transition to Python 3, and many people have "real work" to do instead of transitioning language versions without any real benefit. "3 is larger than 2" is not a real benefit. A real benefit is something like "this transition will radically increase performance" - and no one is claiming that Python 3 has a real-world advantage like that over Python 2. "Python 2 will eventually be unsupported" is a problem, but no one is providing free money to do the transition, so for many people it's just a fact. Historically Python has been very good about supporting backwards compatibility and smooth upgrades. I hope that the Python 2->3 transition was an anomaly. You can make changes to languages, but you have to make it easy for users to do the transition.