Do you think that programmers who don’t code in their spare time for fun will never become as good as those that do?

Question

Programming code can be a really challenging activity

Answer 1

We all do need a break sometime. Read a book, take a walk, go out for some coffee and so on. If you don't maintain those, it's hard to say you'll remain productive and effective as a programmer. Balance is still a must.

To answer your question (I realized I didn't): Not necessarily, but coding for fun or in your spare time gives you more exposure and experience because then you'd have an idea tackling something relevant to what you have done before. It's like in Hackathons, some people who don't do these side stuff tend to have a hard time grasping something new. You pitch something that does not involve their skillset, and they'll think you're talking about building a Teleporting Device.