You are sitting over top of a pile of your own excrement. The smell of your nasty shit is clinging to your clothing more with each moment you stay in there and bask in it.
You should read the book "Perfume". The main character actually blends a bit of human excrement into his Ultimate Perfume, as well as many other every day smells, to make it subtly intoxicating to those who smell it. It ends up driving people mad with lust.
But in all seriousness, I don't usually smell my own shit. That's probably key here. If I could smell my own shit, I would probably be as repulsed as you. I'm repulsed just thinking of someone else sitting with their own shit, since I can smell theirs.
You know, if you really want to read 30 mins in peace, there is plenty of other places than the bathroom.
Hopefully, you flush once you're done and dont let the crap stay in there for 30 mins.
It's an impromptu thing. A Saturday afternoon and my wife is riding me to do the dishes or take some things to storage and my kid and his friends are running around the kitchen island in circles going 'RAH RAH RAH RAH RAH RAH RAH RAH RAH" and I suddenly realize I have to shit and so I go, sit down, and I'm like "it's....quiet..." and pick from the massive fucking stack of magazines I have one the tank that are so heavy they're beginning to crack the porcelain.
I lately started locking the door, too. Fuck my wife for opening the door after five minutes and being like "HEY DID YOU BRING THE XMAS TREE TO THE STORAGE ROOM YET OKAY NO WELL HOW LONG ARE YOU GOING TO BE IN HERE BECAUSE IF YOU DON'T BRING IT OUT TO STORAGE I'M GOING TO AND I REALLY WANT TO WATCH THIS JERSEY SHORE MARATHON AND RAH RAH RAH RAH?" or my kid "HEY DADDY WHAT YOU DOIN' CAN I PWAY IN THE SHOWER BLAH BLAH BLAH".
I love them all and I'm not five minutes from a double murder-suicide. I just ask for 10-20 minutes of meditation, National Geographic, and fecal prostate massages.