You are completely missing the point.
It played no factor in my decision to do it. You are talking about outcomes, which happen with and without drug and alcohol use. And, yes, bad outcomes are more likely to occur with drug and alcohol use (and with many RX medications, age-related decline if reflex ability, sleepiness, screaming at your kids in the back seat, etc).
Prohibition only really works if it discourages behavior.
Truthfully, I am pretty good at monitoring my drinking so I never get close to .08. I've only been breathalyzed once and blew a .03. I'm sure I regularly break .05, but I try to stay relatively safe. And I so rarely smoke pot (nothing to do with the legality), it's hardly an issue. When I do it's just a bit and I typically give plenty of time for the effects to subside before I drive.
When I decide to take the scenic route and make many stops, I take my time. One 4-hour trip took me just over 11 hours. I stopped in a park and smoked a cigar while I walked on a nice path, had a meal, etc. But the point is, none of my behavior is dictated by fear of the law. I just try to stay safe, and would hate to be responsible for hurting anyone--even myself. I live in Florida. A large percentage of the people driving have no business being behind the wheel, even though it is perfectly legal for them to drive.