Fallen from 3.5 mil to 400k GSP What happened, What do I do?

So I've fallen from 3.5 mil to 400k GSP on my main in the last week or two. I honestly don't even know. It makes me feel like I should drop the game after how much time I'm investing in it to be back on the bottom.

I just don't know what happened. I don't know what to do now either, 180hr feels like its just been flushed down the drain.