I think that is an overly simplified (and pessimistic for that matter) view of libertarianism. Yes, Libertarians tend to focus on individuals - individual rights, individual responsibility - let me live my life and I'll let you live yours, etc... But I don't think that necessarily makes us selfish. My wife and I (both registered Libertarians) donate to local charities. I don't have a problem with helping someone who is truly in need.
Basically, where I have a problem is the forced charity aspect. I don't have a choice - I have to pay taxes to the government. Then the government gives that money to whomever it deems needs it. I don't have any say as to whether or not the "charity" is warranted. I don't think it would be well received if I came to your door, pointed a gun at you, and said "give me $500 - Joe down the street needs new tires for his truck." Yet, that is essentially what government does.