If you are using open source you can always support your own old versions ~joking but not really~
Of course security updates are very hard, but if an old version has some good community you have the option of forking or upstreaming the updates yourself
For some languages and applications it can be trivial to backport the changes then trying to keep up with the new features. If it's tested and stable it will likely be more stable than a new version, I do this for some smaller programs and I'm not even a real programmer but more of a hobbyist
Of course security updates are very hard, but if an old version has some good community you have the option of forking or upstreaming the updates yourself