We have a say here in Spain that goes like "Life are four days" meaning life is short and you must make good use of it. My father used to tell me when I bought my first motorbike: "Life are four days, and if you are a motorcycle rider then it's just two"
Marines are young, many of them not married, and with good pay saved from months-long stay on farther lands. When they come back they can buy expensive, fast machines, and risk is not a big deal for someone who is used to enemy fire. No wonder that this cocktail results in so many accidents with fatal results.