I used selective color adjustment layers to get this result. In the Blacks panel, increased blacks. I'm seeing lots of blocky jpeg artifacts. Not sure whether that just because it's a low-quality image, or something else. Also, I'm not sure how black you want to make the blacks. If you go to far, the "subject" (whatever that thing is in the middle) won't be recognizable. Like a black cat at midnight. With a light subject, one fix would be to mask out the subject and darken the background independently, maybe even by painting it in.