Nerd : “socially awkward” and “an intelligent but single-minded person obsessed with a nonsocial hobby or pursuit”
Geek : “a digital-technology expert or enthusiast” and “a person who has excessive enthusiasm for and some expertise about a specialized subject or activity”
So there can be overlap between geeks and nerds, but it’s still cool to be a geek, but uncool to be a nerd.
One of the big things that launched geeks into cool territory is the fact that many of them turned into gazillionaires because of their geekiness.
Likewise, all of a sudden, the geeks are the bosses over their less-geeky counterparts. They’re the ones with the power and prestige within their territory, in contrast with all the regular joes who don’t have the skillset that comes from being a geek.
Having an interest in computers has also become more mainstream as computer technology has become mainstream and become more user-friendly. Pretty much everyone knows how to use a computer, and has interest in technology, whether it’s their cellphone, or their Facebook games, or their Steam account, or whatever. But it’s still rare that you get people who are geek enough to write their own code, build their own machines, or program their own games. So playing Skyrim isn’t enough to give you geek credentials, because there are 10 million other people on the planet playing along with you, but being a pro gamer who participates in tournaments might make you a geek. Reading “The Lord of the Rings” isn’t likely to make you a geek-- it just makes you literate-- but being fluent in Quenya or Sindarian will.
Etc, etc, etc. The bar for “geekdom” is always shifting, as certain things become more and more mainstream.