What does 1 billion dollars made legally through Marijuana in 2015 mean to the U.S. and world?

I tend to look at Marijuana like I do Prohibition in the early part of the 20th Century where they made alcohol illegal and 10s of thousands of people died from drinking methyl alcohol and denatured alcohol that were poor and couldn't afford the good stuff so they just died or went blind by the thousands then.

What I'm saying here is whether marijuana is legal or not anywhere this is dangerous just like whether Alcohol is legal or not anywhere it is dangerous too. Just look up figures of people dying from driving on alcohol or shooting people on alcohol. Then you get what I'm talking about.

Someone once talked to me about driving a car on Marijuana once and they said they got so involved in the Sunset they were driving towards that they completely forgot they were driving a car for about 10 minutes.

Yes. It's true that less people die from from marijuana while driving than people on alcohol driving. I understand this. But, I guess what I'm saying here is one day Marijuana is going to kill more people on the road likely than alcohol does now for slightly different reasons.

Or maybe it's the same reason. People shouldn't drive while high on legal or illegal drugs.

Even legal prescription drugs kill people while driving if they are 1/2 or 1 second too slow in their reactions!

And I'm not sure at this point how self driving cars might help or hurt all this. Likely they are just going to complicate matters even more than they are now.

Imagine someone completely high on alcohol or Marijuana or something else or both and riding in a self driving car that has a steering wheel for a licensed driver to rescue everyone in a digital emergency.

There is a crash caused by the technology in the car. Everyone is high in the car. No one knows where they are or even who they are during or after the crash. Who are they in this self driving cab?

Who is liable for this self driving cab crashing into another self driving cab with other high people in it too? Both cabs were legally required to have a licensed driver on board watching over everyone. Is this person liable for the crash in both cars? or are the manufacturers of the cars or is the Solar Flare that just hit and fried the GPS satellites liable for the crash?