I wonder what the retention rates are for low hours co-pilots actually staying in the North Sea for > 5 years? Most of the ab-initio co-pilots I know moved on after a few years especially those whose original plan involved something more 'exciting'. The ABZ North Sea is a novelty while it lasts for many people, once they have a couple of thousand hours doing it, it soon becomes a means to an end. Sure, a good way to earn a living, but ultimately not something that people go home and dream about doing all over again the next day. Many co-pilots will use their experience gained to branch out into other sectors, such as HEMS, police or VIP perhaps, and I would say that is what will likely happen to yourself as you will hanker after 'proper flying'. You will probably move house three or four times until you eventually settle somewhere that ticks all the boxes: job satisfaction, money & location. And then, just as you think you've cracked it, the contract you are working on will disappear and you will have to move back to Aberdeen back to where you started. Most people end up back there eventually
However, you will have a few stories to tell your brother, who will by that time have expanded the company business to a multi-million pound empire, which you opted out of long ago.
Fortunately, I didn't borrow any money to start my flying career, but I did opt of a family business, which would ultimately have allowed me to buy my own helicopter and do whatever I wanted. I didn't see that at the time, and I have had some great experiences, but I do think being comfortably off through self-employment must offer more freedom and choices than being stuck in a career that just about pays the bills, however nice the view is.