Well, I don't think Gaga is pop culture trash, or that she only has 15 minutes of fame.
She has been constantly mentioned in the media.
She has many number one hits (Bad Romance, Poker Face, anyone?)
Her music is for the most part, very, very good ( if you are into this genre).
But most of all, her fans are truly fanatics.
I should know. :) There's a personal connection between the artist and the fan.
For example, fans refer to her as Mother Monster and to themselves as Little Monsters.
Also, they take great interest in her activities and her well-being.
There's even a university course on the subject. So, with so many hits, so much mention in the media, great critical reviews and dedicated fans, she clearly is not just basking in the sun.
She also sings live at all her events, unlike many artists nowadays. She is an extremely talented vocalist, no matter what you may say about her composing (which she does by herself).