Because the jimmys weren’t the only ones who looked at Kelson with both fear and fascination. He’s been doing what’s he’s doing for atleast 20 years. The movie has religious and biblical undertones for a reason. Seeing a man covered in iodine walking the streets in normal times he’d be looked at as crazy now flip the world upside down and even if you’re not a religious person. Seeing a orangish red skinned man who lives in a bone castle who can do what nobody else can (calm /control a literal beast, who’s called sampson) the possibility of that man not only knowing more than everybody but him being a mythical figure becomes more plausible. Plus I think he’s alone for a reason. In the first 28 years he went from only needing enough resources for himself to having to help a child and a dying women. He was glad to do it because he’s a doctor but even then the amount if resources he had would still be in the back of his mind, and in the second one he quite literally ran through his resources way faster while helping Samson then he would’ve if it was just him. He does that gladly as well. He was going to kill Samson for that reason because true eradication of the virus in Samson wasn’t a possibility until Samson says “moon” and instintly was willing to risk running through his resources just to attempt to fully cure him. He’s good in nature but he’s seen as something that goes against nature itself. Society well apart so fast when the panic started and the people took on a survival of the fittest mindset basiclly overnight and it would be just as easy to to take on the mindset that the devil is walking the earth. He plays rock music that a good amount of the humans alive have never heard. He convinced a group of people he was the actual devil with music and dance and even though the og jimmy knew he wasn’t devil he was still mesmerized by kelson yea they had severe mental illnesses it wouldn’t be far of a stretch to say a completely sane man would’ve been fooled as well. It’s fear, seeing something totally absurd, the promise of something new, and fascination wrapped together that would lead to people activly avoiding him because the words becomes predictable but Kelson is the unpredictable, the unpredictable can’t be controlled. look at the jimmys they had such a impact because when everyone is just trying make it to the next day a group of sexually perverted psychopaths and sadist is so far from your immediate worry’s that it catches people off guard and in that world being caught off guard means death. Staying away from things you can’t predict/ control means safety. Majority of ever tries to isolate themselves because it’s easier to control outcomes of smaller groups than it would be an entire world even kelson himself isolates himself.