[wpietri]

I second this. The fields the OP mentions in particular are all quite hard to making a living at right now. Journalism is especially brutal these days due to the decline of newspapers. Keeping the (lucrative!) tech job while building up skills, connections, and a track record is an excellent way to do it. Tech is also the kind of field where you can do part-time consulting and still make enough to get by, which can really help with a transition into the new career.

As for people who have done it, an example that comes to mind is Daniel Suarez, an IT consultant turned novelist: https://daniel-suarez.com/

I'd also recommend digging around for John Scalzi's recommendations. He's a former finance journalist turned novelist, so he has a lot of good advice about the practical and financial side of becoming a full-time writer. For example:

https://whatever.scalzi.com/2008/02/11/unasked-for-advice-to...