Yes, the $9k is insane. But it can work for some people, especially if you can time it around some big expenses (insurance premiums, home project, etc.)

I've done it once for the 50k. But the card was also very useful for me to save 10% on BA flights. If you're travelling with your family, for example, that can add up to a pretty big saving. And, incidentally, paying for that trip on the BA card gets you get 2x BA points on BA ticket purchases and that kind of trip will get you going on the $9k spend.

Not for everyone, but the card worked for me in the past and I'll likely get it again.