Comment by epolanski

I'm just talking about my experience as a former researcher.

If you spend 10 years of your life working on dye sensitized solar cells and perovskite, the number of positions for those roles in your area/country might be limited or non existent and at the same time you may no longer find any funding at your current position.

Thus you need to look for jobs outside your sphere of conpetence and for those your PhD may not be that useful, if not even a malus.

I have a friend who has a PhD in applied mathematics, has spent the last 5 years of his life on deep and machine learning problems, and he's applied to several positions as an ML researcher and his CV is not considered often due to the lack of professional, non academic experience.

And we talking the very booming ML sector for someone who understands the ins and outs of the math and architecture behind the models (area: UK and northern Europe).