I'm an Australian with British ancestry and I moved to the UK 22 years ago.
First thing, sponsored? As in someone sponsoring a visa? Unless you have exceptional experience/talent, it probably won't happen. You'll need ancestral rights or a spouse with them.
There are ways of immigrating but you'll need to check the respective country's websites.
License conversion costs depends on what you have already experience and license wise. It's not cheap. Ireland is still in the EU, the UK is no longer. Therefore, that will affect what license you go for.
I fly for NetJets Europe and I'm on over €150,000. A compatriot of yours works for NetJets America and she's on well over $220,000 (FO, I'm a captain).
Economy collapse? Who knows? Might do. Might not.
Definitely can feed myself on that income. Not a problem at all.