I have no idea why they mention coding. It is the same in any kind of job. You can bake cakes for fun, make music for fun, write poems, novels, play chess for fun, practice sports, grow potatos ...
At a certain stage, you realize that in order to be able to do only that job, you must make someone pay you for it. You must do it in a way (or in a volume) which makes others happy. The fact that it makes you happy is not enough anymore.
I don't think there is an angel and a devil. It is still the same thing. If you like the result of your work, there is a high chance that others will like it. You don't need to change what you do by a 100%. Changing it by 5% - 10% is often enough.
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