For me it's two things, comfort and the inevitability of the wetting/swelling "process" I guess
When I was like 7, my little brother was in diapers that could fit me. I thought they look cool and must must be so comfy. I remember I would kind of sneak and examine a new diaper and LOVED the ruffly leak guards and thought they must feel so nice and hopefully a little tickley.
I finally did eventually try one on and liked it but was too scared to keep it on long.
Now for how I got hooked.
When I was around 12, I bought Goodnites, The last of the BIG ALL WHITE ones. It would be my first time wetting since I was a toddler. I was just expecting it to feel wet and probably get cold quick and that's it. Boy was I wrong.
I still remember it
burned into my memory. I was home alone and in front of the mirror in the bathroom. When it first started I felt nothing for like 2 seconds but saw a grey circle quickly go from dime to half dollar size in that time. I remembered thinking that was weird but didn't get time to ponder that. Suddenly the stream broke from what I now know was "direct injecting" the padding and suddenly started now making a surprising hissing noise. instantly the gushing warm flow spread around my privates and felt so unexpectedly good.
Then I started to actually feel the gentle constriction of the swelling starting. Now in the mirror I could see faint rising horizontal line of lightish greyish yellow rising up the front of the diaper along with it starting to puff. My void slowly stopped. Even after I stopped, it continued swelling which I thought was soooo cool. It was dead silent in the bathroom and I could hear the diaper gently popping and crackling while it finished swelling. I stood there completely amazed by how this all actually felt compared to what I was expecting. It was just so cozy, warm, and soft with a gentle hug-like pressure too.
Needless to say, by the time the diaper was done swelling, something else had swelled up as well.
Now I would say I'm addicted to how comfortable diapers are and also the routine and inevitability that I WILL experience wetting several times throughout the day with NO EXCEPTION and the diaper WILL be SO SWELLED and comfy by the end of the day!
That's what they're for and how it WILL be. It's just such a calming, comfortable bliss!! I don't know how else to describe it really. I use Megamax diapers now and they're awesome.
I still adore the fact that diapers have those ruffly leak guards too!