I'd be very careful choosing aviation as a career path. The important message in my post was ' It's all down to LUCK'
The FI/IR question is another matter all together. I know people with both that are looking for work.
I know FI's that are desperate to move on for a number of reasons, yet cannot afford the IR, or whom question the state of their sanity if they wait till they've reached some ever changing magic number of hours (SOME of them wish they'd done the IR instead, others don't).
I don't know anybody with an IR that is flying IR twins that would choose to change jobs and become a full time FI on single pistons
As an FI where does your career go????? Once qualified and with low hours, who do you learn from????