This makes no sense as staying cognitively active has been shown to delay dementia: https://www.health.harvard.edu/blog/can-physical-or-cognitiv...
Key excerpt:
> These studies are important because they show that, despite an equivalent amount of Alzheimer's pathology (measured at autopsy in the first study and by blood in the second), individuals who were more cognitively and physically active were able to delay their clinical Alzheimer's disease diagnosis and cognitive decline. This means that even if you are likely by family history — or bad luck — to develop Alzheimer's disease at some point in your life, you can delay the onset of the disease by staying cognitively and physically active, and you can start at any age.
As for physical activity, that's a lifestyle choice and has nothing to do with working in tech. At least for me, working in tech is keeping me cognitively active. It's hard for me to even imagine a scenario where that wouldn't be true in tech.