I agree, roughly, with cristo when he says that in order to get a place in a cosmology PhD programme you need top grades and to demonstrate an ability to be successful in a research programme, but this is the same for any PhD application.
But, in practice, to do funded cosmology research you need to do the right courses, know the right people, and have a lucky break. It's not an area where you can say, I like this, I've got top grades, so I'm going to do it, and I'm going to have a career in it. If you are interested in research and development of computer hardware, then you can say this!
I remember a long discussion in the computing department where everybody was talking about how they started in electronic engineering, physics, chemistry, cosmology, whatever and couldn't continue in that career, and had slipped into computing...
So all I'm suggesting is that the OP might have a happier, easier life by going into computing (or stock brokering...) in the first place, rather than ending up there after traveling along a convoluted, weary, and financially impoverishing cosmological diversion. Or if he must do physics of some kind, then perhaps other areas (like accelerator physics...) might provide a more rewarding career path.
Then again, cosmology might be *the* calling for him, and if so, I would say, "go for it". But all this "I like money", and "I fancy stock brokering" talk doesn't make it seem like a true calling to me.
