I have always thought encryption is fun. Mildly fun, not worth a whole lot of my time or intellect but an amusing exercise for Sunday afternoons or when lying in bed only about 25% asleep.
In saying this I am thinking only of encryption. Decryption is another story, usually boring, hardly ever worth the investment. There are several reasons for this. The information which has been encrypted is usually of low interest and so decrypting it provides little reward. Most decryption is ad hoc; it will not become a long-lived service on which my future life can be built. Most significantly decryption is not typically creative. The creativity is embedded in the encryption and the process of decryption merely undoes what someone else has already done.
This last point touches on the core of who I am. I am an on and off creative, a programmer, a synthesist, a builder of sorts, and a systematist; I am not a bookkeeper, a hacker, an analyst, or a building trades craftworker (even though I can do some of those things). I use my computer to create posters advertising the chapters of the Gospel According to John; I hate being forced to use Word, Google Search, other people's websites, or DocuSign. At intervals I have painted pictures, taken photos, and assembled fanciful trees out of wire but I have trouble building up much enthusiasm for public art installations or for churchy curricula pushing the contemplation of a reproduction of a semi-professional colored drawing by someone who is neither an Albrecht Durer nor a Norbert Kox.
And so encryption: On and off encryption can be fun because you do not do it every day and because it permits you to creatively identify a new way to build an encryption algorithm out of parts which you have lying around. Because it is a mental challenge. Because that challenge may have a parallel in some other problem you would also like to solve. Because each encryption is different, just as different as you would like to make it. And because in my actual reality it is entirely uncoerced; nobody in the entire world cares whether or not I accomplish the encryption or how good my technique proves to be.