I think Sony shot themselves in the ass w/ the release of the PS3, specifically not putting enough units out to cover the initial demand.  I don't think of myself as a fanboy but i always preferred the PS until the PS3 release.  The prices they were getting on e-bay were beyond insane.  Enough said on that, back to topic. 
For a company as big as MS, $50mil isn't such a big deal, especially if they spend it to corner a market.  They buy an exclusive 
on a hot title & they know people will buy their console to get the exclusive content.  In turn, the sales of their consoles go up. 
Now a lot of people have a console they spent a bunch of money on so they buy other games for it.  On top of that, they claim 
the original $50mil as advertising & write it off on taxes. 
In the end they get it all back + more. 
As Homer Simpson said, "Just because I don't care, doesn't mean I don't understand." 
Either way, I'd hate to see MS get control of R*.