Stronzo, I'm so sorry about your brother. Bless you.
As for why people do it, I can almost understand. I think most of us look for new sexual thrills, especially when we're young and still discovering the joys of sex, and when we're older and trying to spice things up.
Few of us are satisfied with one masturbation technique, or even just masturbation for that matter. We want sex, and not just coitus. We want oral and anal. We want multiple positions. Some of us want threesome or groups sex or toys. Some us costumes and props. How about fisting? And so on.
If I heard about a technique to significantly enhance my pleasure, I'd certainly be interested in trying it. I'd rapidly lose interest if I learned it involved something risky, but I'm sure many men, especially younger guys, don't fully realize the dangers of this practice. They've just heard or read about how amazing it feels, and their source of information may downplay the risks, or offer instructions on how to do it "safely." Even if the person engaging in the practice is aware of the risks, I'm sure there's an element of "I know what I'm doing; it's not going to happen to me" kind of thinking.
There are also parallels to drug use. Over the years I've met several extremely smart, well-educated, "respectable," professionally successful men who use recreational drugs and are very casual about doing so. As far as I can tell, in their minds, there's no good reason not to do drugs. To them, the high is worth it--they typically downplay the risks.
[I've noticed that there's no small degree of arrogance among drug-users who are not yet addicts, or who have not yet had to face the consequences of their addiction(s). They see themselves as different from, and superior to, the people who end up in jail or in rehab. The greater their professional or social status, the greater their sense of privilege, of immunity to the consequences of their habits.]
There are also some parallels to extreme sports, daredevil stunts, and other "legitimate" forms of thrill-seeking, except that I think these people may be more realistic in their assessment of the risks, and more responsible in their practices.
Among human beings, there is a wide range of risk tolerance, from abnormally low to abnormally high. We all know (or know of) people who engage in risky behaviors in the pursuit of money, power, status, or pleasure. Then there are people (like me) who avoid risk to the extent of denying themselves opportunities for personal or professional growth. Many (most?) people are a blend, willing to take risks in some aspects of their lives but not others.
All that is to say that I think autoerotic asphyxiation may be a type of thrill seeking, and thrill seekers often have a high risk tolerance and/or an unrealistically low estimation of the risks of their behaviors.
