Blackouts? What causes some to have them, some not? It's very scary, and potentially dangerous, Too much alcohol consumption?

It seems that science isn't exactly sure what causes alcoholic blackouts but there is a strong indication that what makes them happen is a rapid increase in the blood alcohol concentration. So, it isn't necessarily how much you drink but how fast, though the amount has something to do with it. Have three drinks in 10 minutes and you aren't likely to black out. Have ten and you might. Have the same ten drinks over a period of four hours and you won't. Why some people get blackouts and some don't is probably as simple as that: some people drink at a moderate rate and some don't.

Yes, too much alcohol is usually the cause.

Sometimes, or dehydration, or smoking.