By taking advantage I mean buying out AAA third party exclusives.  Hear me out first, I'm not talking about games that have equal sales on PS and Xbox, I'm talking games that have a majority of their software sales on PS.  We see Sony doing this for small games like bloodbourne, where the souls games get a majority of their sales on PS, but I think they are missing out by not doing this on bigger games.

My first example is FFXV.  We all know FF sells way more on PS, last gen FFXIII sales were more than double on PS and Sony and SE have a great relationship, they would just have to pay SE for the lost sales that would have been on the X1.  FFXIII managed to sell 2m on the 360, and considering Xbox does not have the advantage this gen, Sony wouldn't even have had to pay for 2m worth of software sales, it would have been way less since they are in the lead.  Going from FFXV Sony should have bought exclusivity for KH3 along with that since KH has never been on an xbox console and I can't see making KH3 exclusive costing Sony that much.

My next example is MGSV.  MGS does not sell well on Xbox, GZ sold over 4x more on PS4 than X1 and on last gen its even worse with it selling over 5x more on PS3 compared to 360.  I would reference the HD collection but only the Japan sales are on VGC.  This would probably be cheaper than getting exclusivity for FFXV, MGS has virtually no fanbase on Xbox and yet Sony doesn't buy out the game?

I haven't heard anyone on the site talking about this so is there something that I'm missing as to why Sony is not capitalising on these games?

Because it's probably not worth the investment?

Sony doesn't have the money :P

I can't see the investment being anything major when a game like MGS sells 4-5x more on PS. 

Probably talking about millions here. Especially since MGS is an established franchise.

Bigger publishers like SE, EA, and Activision no longer care about catering exclusively to Sony.

In previous gens, since the hardware was so different, it made sense for publishers to develop exclusively for the PS2, especially since it had such an insane lead.

Now, a game can easily be ported to the Xbox One or vice-versa due to near identical architecture, so you're losing massive money by keeping a game exclusive. Sony would have to pay a lot more than 2-3 million for exlusive rights to FFXV or MGS.

Its an established franchise on PS, not on XBOX.

I realise they no longer care, which is why Sony has to be the ones that go to them and offer the deal.  They wouldn't be losing money since Sony would be paying for the lost sales they would have had on the X1.

Because Sony don't bribe somebody to only do a game on their platform. They earn it.

They probably could match the money those games would make on Xbox but i'm not sure it would be worth it in number of PS4's sold, and if those games aren't selling well on the Xbox anyway. Such an investment to drive sales may be better spent on, I don't know, first party, advertising, whatever Sony think will produce the best results. That being said they have always had a great relationship with square, fantastic compared to microsoft so something like a timed exclusive for KH3, would probably cost pennies.