I don't think Phil actually believes he's going to be attacked if he does things outside, but I do think he sees it as the perfect excuse not to and probably gets a little thrill fantasising about being notorious enough that people would want to fuck with him.
I used to be in that camp when I first started following Phil, but now I think it's a legitimate concern. Detractors really live rent free in Phil's head, and because he's been a hermit shut in for so long, he's feeding into his own delusion. And he's shown to be overly paranoid about his safety before, it's a big part of why he doesn't want to go to Walmart. Yeah, part of it is an elitist mindset of not wanting to shop with the poors, but part of why he doesn't want to be around them is he think he'll be stabbed.
There was one incident that really stood out to me, early Covid, where he said he finally went to the store and was shocked how peaceful it was, like he was expecting some kind of warzone where he'd have to bust out his hatchets. Speaking of, I'd argue that's another example of paranoid Phil. He tried to mask it as being tough guy Phil, but I think he actually felt like he needed the self-defense. Phil is also just a massive pussy, he's too cowardly to even talk back to a kid on VR chat when they can hear him. Obviously, he wasn't always like this, there's footage of him out in the wild and stories of people interacting with him, but those are from like, 20+ years ago now, and Phil has definitely devolved in that time from his hermit lifestyle. I think the biggest nail in the coffin was Doordash becoming widely available in the last couple of years. I don't think Phil even goes out anymore on his day off.
It's probably not solely out of fear of being attacked specifically, laziness is certainly a big part of it, but I think the more Phil has embraced the hermit lifestyle, the more it's naturally fueled his paranoia. He might actually think of it more as "you're safe in your snortfort, why leave it" as opposed to "you'll be attacked if you go outside"