Six options:

1) Low rate of success is coupled with a very low investment level. 2) The behavior isn't to try to pick up the woman at all but rather to engage in shared bonding among the males. (Note how this behavior seems to generally occur when there is a group of males.) 3) Lack of self-restraint. The people in question who do this are typically low status and low income. There's a large body of evidence that people with lack of self-control have less life success. (The marshmallow studies and all that.) Some of these people may have little self-control or bother so little to exercise self-control that clearly unsuccessful behavior is still attempted. 4) Attempts to harass the people in question, possibly to blow off steam at one's own lack of sexual success. 5) A well-meaning attempt to actually complement people for being good looking and well-dressed. They may just be unaware of how uncomfortable this behavior often makes women feel. 6) Possibly combining with any combination of the above possibilities- cultural behavior. Once there's some small fraction doing something, how long does it take before the same behavior is imitated in the general group?