>>212940377 (OP)Unlike Kal-el who didn't grow up in Krypton and having no attachments to it besides the video message of his parents, Kara DID grow up there, had family and friends that she loved and spent time with, and presumably did fun things there.
The planet where all of that happened is gone, and so are all of the people on it.
She's a drunk asshole because unlike Clark who grew up with human parents and knows how to deal with things and keep moving on, she had no one she can turn to.
So she just copes with partying and substance abuse
Would not be surprised if Jimmy will be her love interest again and causes her to actually care about something now