3" tire cruiser should be more than adequate for street riding under 20 mph. Above that, I prefer a full suspension bike for that damn manhole cover you failed to see. Or at least a long bike, which is harder to stand on the front wheel at 30 mph.
I crack up on the fat bike riders I see around here. I'm surrounded by a few trillion square miles of sandy desert, yet continually see fat bikes riding on the street. I have yet to see a fat bike in the dirt, or even a track of one that was there yesterday.
Rolling resistance? I don't know, but one fat bike rider I see all the time is getting a hell of a workout trying to keep up with his wife. My guess it's just bike weight, plus his weight, rather than the tire per se. She's on a 30 pound bike, and weighs 120. He looks like bike and him weigh at least 50-70 pounds more.
Put a motor on one, and now a fat bike sounds like a great idea! Even a pussy motor like the storm will have. But a guy building a fat bike to do 50 mph is IMO, heading for the E room. At speed you need shock absorption, damping, not just springy ness.
I think a fat bike to do 25 mph would be great fun, especially in sandy deserts or beaches. But in the desert, might need 4 pounds of slime per tire.
One nice thing, the thorns would only go in the bottom of the tire, rather than in the bottom and out the top, as they sometimes do here. Note the length of the thorn in front of the lighter. And they get even bigger in TX or AZ.