Survival? I don't know, I've done it. And I regret it, but I've learned my lesson. I think people just like to experience it themselves, and then get hurt, and learn by their own mistakes, rather than listen to someone else that did it and warns that they shouldn't do it because it's a bad idea. They probably think they won't get another chance, "Maybe this is the only person that will ask me out?" kind of mentality. I've done it, and it was stupid. People are stupid.
The logic (from what I've seen and done research on [in my head]) is that these serial daters believe being alone will give have past traumatic experiences show up in their lives. In most cases, serial daters tend to have had a bad past, one that they cannot get over, and tend to just date people in hopes that it'll at least close the wound for a bit. This usually leads to drugs, because they tend to get into the wrong crowds at times. Not sure if I used the correct phrases... I'm tired.