Don't know if this is good enough to complete not easy with the hair

You couldn't have a chosen a harder source to start cutting with

It's not too bad, all things considered, but it's much easier and much quicker to get remove.bg to do the heavy lifting for you

Crop the source image to include the area around the head only, like the attached file. After all, the sky above his head and anything beneath his upper chest is irrelevant to us. Then put it through remove.bg, which gives the second attached image.

It needs a bit of cleaning, a small bit of rotating, brightening and cropping after this, but it's only a minute or two's work