Maybe, but an experienced (instrument) flight instructor will almost always have the edge in learning curve and survivability over someone with 500 hours TT who just flew around the airport doing not much.

One thing that instructing does for you is that it forces you to manage your resources and it quickly grows your confidence level in the airplane since you are the PIC in charge of someone who does not know what he is doing. It also develops your knowledge and study habits to a point of understanding where you will be well positioned to tackle both part 135 and 121 training later in due course.

Even if I myself as a new CFI-I with 500 hours TT could go to work right now for a IFR 135 operator, I would decline. Just the mere process of earning that CFI-I has awakened me to how much I DON'T know about flying. I don't even want to fathom how a circling approach to mins would be like in icing conditions and at night....

You'd better bet that those insurance minimums and gov't regulations set the bar so high. They're that high because experience does really count.