I don't think you understand advertising. I can guarantee you the average 55 year old......hell the average 55 year old BULGARIAN earns more per year and has more free cash flow than the average college kid. They would be very valuable to companies that sell to that demographic.
College kids have no income or very small fixed income
Don't bother arguing with him, he has no idea what he is talking about.
That's the whole point of Facebook - extremely targeted advertising or extremely broad advertising. You can go on there today and put an ad up for your product and make sure it only hits who you want, let's say - 40 year old single women from texas with over 500+ "friends" and who like Michael Jackson. Or, you can just do 40 year old women and it will display your ad accordingly.
Face it, Zuckerberg won and I don't see Facebook going away like myspace, etc. In fact, I would say it's a solid investment when it goes public. Zuckerberg knows what he is doing as CEO...and is obviously not in it for the money.