They got data lock in with Photoshop and Lightroom. Admittedly, the free alternative just doesn’t work as well as Photoshop or Lightroom.
The SaaS is on a monthly or annual subscription. So spending $20/month, if you only use it for 1 month, is far cheaper than spending $800 outright for a Photoshop license. And now, Adobe has the potential to reach a global audience of 7 billion people.
Of course, there is some risk that your code will be pirated, decompiled, and reassembled, to remove the ET-phone-home feature, but this is only a minor annoyance. It’s better to get your product pirated, than another competitors product. That way, the people using the pirated copies, who are likely poorer, or kids, will learn your program, and eventually pay for a full commercial license eventually, when they get a job professionally using the product.