I don't exactly agree on why employers prefer PhDs even if not exactly in the field.

Having PhD shows that you have committed to one field hard enough and long enough to be granted the title even if it is PhD in philosophy.

Also, if you switch from another career try to figure out how you can use your past experience to differentiate yourself from other people.

For example, I have studied theoretical math and I have spent 20 years as software developer working on varied projects from embedded to algorithmic trading to backend to frontend applications.

I am currently switching to electronics and will use my knowledge to work on projects that require high level of both math and software engineering skills. Think in terms of realtime control systems, building reliable and performant stuff (reliability to differentiate from competition), etc.

Never think of moving as rebooting your career. Always start with mindset of building on top of what you know -- always move forward, not backward.

A little change in mindset goes a long way.