Looking back of the responses, I think some posters interpreted my claim as "prep is the same as playing an RPG" (a claim I never made), but when what I mean is that it feels playful and fun and an exercise of the imagination.
I see the point. And maybe I'm going to be a bit picky here, but i think it is in line with your later comment about understanding things...
I don't know that prep has ever seemed "playful" or "fun" to me. When I've done a good job, the feeling is best described as satisfying, and when I am not too pressed for time, it is usually enjoyable. When I am very pressed for time, it becomes work, and less enjoyable, mostly because I don't have the freedom to really sink into the activity.
And I say this while I am generally in the midst of prepping up a new campaign, and specifically in the midst of prepping up a one-shot for a house-con this coming weekend.
I think considering exactly what words we use to describe things can be helpful. I'll use another hobby as an example: My wife does a lot of fiber arts - she preps fiber, spins yarn, and weaves, crochets, knits, and does needlepoint. And she describes different activities in the overall hobby with different words: Blending fiber before spinning is playful. Prepping up the loom is like a complicated puzzle. The act of weaving is meditative, for her, and so on.
For some others it seems that thinking about anything is overthinking it
Yeah, not that. I'm fine with prepping, as a general concept. I just have enough demands on my time that I can't really engage in it for its own sake.