"This makes me wonder. Who is actually using Photoshop today and why?"

Photoshop has unrivalled features - not just photo editing, but also digital painting, animation and even limited video editing. At one time, Adobe even added 3D features to Photoshop (which they later removed). Photoshop also supports a massive market of third-party add-ons like plugins, brushes, scripts, effects, LUTs etc.

In a different comment, I mentioned that no other software can rival Photoshop in learning resources. So yes, Photoshop is a monster in features, bloat, in clunky UI - and still dominant in design and photography fields.