Hm. I meant to say that "The Amtrak-run NEC is decently run."
Is it true high speed rail, no, but at this point the startup costs of actual high speed rail are so high that private entities pretty much never take it on. (Brightline in Florida is not actually high speed rail due to the speed, Texas Central is floundering due to lawsuits, Las Vegas to LA is on constant life support, etc.)
The only profitable private railroads are the ones that started off with cheap property to develop near stations and never sold it off, essentially becoming landlords/property developers in their own right. But the horse has left the barn for that in the US and nearly all city center property is expensive for a singular entity to just buy up and redevelop.