I can only speak for my personal experience - I write all my new code in Py3, and almost every still-developed library works great with Python 3.. The authors usually ported it several years ago.
But sometimes you&#x27;ll need something that&#x27;s not still supported -<p>Perhaps you want to parse an old obscure file format, and the only code you find for it is from a usenet post in 1996.
That code isn&#x27;t being updated, and no one has ported it.
That means you need to do the work to update it, and that can be hard when you aren&#x27;t familiar with what it&#x27;s supposed to do.<p>The other place I&#x27;ve seen people sticking with Py2 is when they&#x27;ve got a huge chunk of internal code.
Some companies have been writing python for 20 years, and the original authors have long since left the company.
It can be hard to write a business case for having someone spend several weeks updating all the old code, particularly if it&#x27;s purely internal, and doesn&#x27;t touch the internet.