pics

I used Photoshop professionally for nearly 30 years. I retired and don't need it anymore, so now I use GIMP on Linux for the few personal projects I want to make.

GIMP's interface leaves a lot to be desired. One example, in Photoshop the Channels tab shows all the channels and includes any masks you make, they look and work similarly to the layers, and it's intuitive--when you learn one, you know the other. GIMP doesn't work that way, in fact I've yet to make sense of the channels.

Also, typically one would expect filters to only be applied to a selected layer and even to a selection within that layer. Some GIMP filters apply to the whole image, flattening my layers, and creating new ones. Fortunately, these are made in a new document, so you don't lose anything, but the filter cannot be applied to a partial image, you'd need to pull the result back into your original image and mask out the part you wanted. Very strange.

I could go on about how selecting works and doesn't work, but I won't.

No, Adobe has not "lost millions" due to GIMP, they haven't lost a cent. People who use GIMP were either never going to pay Adobe a cent, or already have and are using GIMP now, for similar reasons to my own. Virtually no one uses GIMP professionally at any volume of interest to Adobe.

It's a good and useful tool, but it's severely lacking compared to Photoshop.