What a good question. In fact I gave this some thought already many years ago.
I still think that every individual could have a different reason for, or perspective on, this matter, but here is mine:
I have always wanted to pee and mess freely since I can remember. I do not have a pee fetish (although I do have one for squiring women), nore do I have a poo fetish. If someone does; also good! I don’t judge.
So like I sayd, I’ve always wanted to pee and mess diapers, for as long as I can remember.
This was a long and hard struggle through decades. As the years went by I more and more came to peace with it and learned to enjoy it a bit more. Less guilt to be specific.
I think the question “why” arose 10-15 years ago. And I found the first answer pretty quickly, which is: the feeling of fluids pressing up against my genitals is very nice and a diaper is always ‘there’ to be felt and the wetter it gets the more it presses. As for number two; it just feel naughty and it also has a nice sensory feeling. The smell is also a very double sided thing. On one hand it’s not that nice to smell poo, but on the other hand it’s a very clear reminder that you have a full diaper.
The second answer that I came up with fell into my lap when I met my big sister and my little was triggered in a different and much stronger way than before. Whenever sis and I are together (at home, event, con, shopping, etc.) I have a strict no toilet policy and have to use my diaper. This arrangement makes sure that my little is constantly triggered and thatis just good for my soul. It makes me calm and it soothes me.
Love,
Spike