Over-dosing vodka by a factor of 10 will likely be scary for your family in the hospital. Same goes for nutmeg.

Part of the danger of a substance is how much distance there is between the substance doing something intended and something unintended by taking a higher dose.

Part of the problem of the opiod endemic in the US is that fentanyl is so potent that due to fluctuations in the incompetent black market on it, and/or due to incompetence by its users, things can turn deadly quickly.

The other thing is how long it takes for you to notice the effects of a substance. If you get a quick result it's far less dangerous to overdose, as you'll notice when it's enough.