Jesus you are desperate to prove something here aren't you?
This is a chart of per PC profit. Let's break that phrase down:
"per" -- this says nothing about industry-wide profit, which you would need to address in a discussion about whether or not the industry is in decline. If I said that profit-per-telephone for rotary phones was the highest ever this year, would you be convinced that the industry is doing better than ever?
"PC" -- not just laptops. This graph goes all the way back to 2006, when laptops were hardly as ubiquitous as they are today.
I don't understand what you're trying to do here. The industry is clearly in decline by every accepted measure. Even if we go by your chart, any industry whose major players are doing worse than (or at best, about even) with their numbers from 8 years ago would be said to be declining. Not stable, which is another term with a specific meaning, and also not what you think it is.