But if you throw 2 discs exactly the same way, say a PD and a Destroyer and the Destroyer goes 20 feet further on the same line, was it really riskier to throw the Destroyer? It is riskier for you if YOU are more likely to mis-throw the Destroyer than you are the PD, but I don't think it is inherently riskier. If you are more used to throwing the Destroyer on that line than the PD, then I'd even say it's LESS risky to throw the disc you know well.
I would agree with you that reaching for 20 feet of extra distance on a hole where it doesn't really matter is not a good idea, but that's as much about how you are throwing as it is the disc speed. I can throw a PD on a riskier line to try and get more distance with it just like I can with a Destroyer or Scorpius. In that case it's the throw that's risky, not the disc selection.
When it comes to magnifying mistakes with more distance, there's always a risk-reward proposition. It's definitely riskier to throw farther but in some cases the risk may be worth it. I could just always throw mids on safe lines and never throw more than about 320 feet, but there are plenty of holes where it's worth the extra risk of throwing a driver to get to 380 or 400. If it gives you a putt or gets you around a dogleg and in view of the basket for example, it may be worth the risk. I mean, look at Blue Lake holes 3 and 18 for example. If you don't throw a big enough hyzer to make the corner on those holes, you have zero chance of getting a birdie and much lower chances of even a par. In that case, the risk of going OB into the bushes may be worth it if you can make the corner consistently.