She gave up her company and private life long before that. Just, she didn't do it by blowing the secret, she did it by letting this extradimensional demon thing (not to be confused with extradimensional imps like Mxy) masquerade as her at work and sort of take over the maintenance of the Karen Starr identity, while Power Girl continued to be Power Girl full-time. (Because the demon had already been doing so for months before she even noticed, she figured there wasn't much point in fighting for an identity she didn't use.) This was, like, back in the Bwahaha League era. There hasn't really been a Karen Starr since then, until this series launch.