It’s with one of the Amex cards that offer a 2-4-1 BA ticket.
The unusual thing here is the actual ticket initially costing £15K - Ultimately, you’d end up using the same number of points if the ticket only cost £3K (assuming the flight was to Mumbai).
So I guess if you want to feel like you are getting the absolute most for your points, you want to find a flight that is overpriced, and then use your points on it.
Prime example was my flights to Lanzarote last year (family of 4).
I could have probably got them for around £700 or £800 depending on what “extras” I went for (maybe slightly more).
The BA flight I ended up booking would have cost £1850 if I’d simply booked through BA (It actually cost me £115 in taxes, because I booked with my BA points).
So, did I save £1850 (minus the £115)? In a way, yeah I did.
Would I have spent £1850 on flights to a volcanic rock… No - If I had to, I’d have bought the £700/£800 flights from a budget airline.