For things that have a risk of damaging a real system (Inserting INTERNAL connectors or cards with the power on, booting with no heat sink, overloading a PSU) there should be an RNG chance of the part(s) in question becoming broken (the PSU itself if it's overloaded, the CPU if you boot with no heatsink, etc.)

It shouldn't be a certainty, because it isn't in real life either. Many things are designed to protect themselves from at least modest fsck-ups (after all, a CPU fan can stop working through no fault of your own, and you'd want the CPU to survive)