OK I'll preface by saying I'm relatively new to bitcoin and not a computer guy.  Hopefully someone can explain - I hear about a "51% attack" where if any entity ever took over 51% of the computing power of the network, it would allow them to control the blockchain and, in effect, bitcoin.  As I understand it, miners collectively "control" the blockchain now.  So according to this chart:

https://blockchain.info/charts/miners-operating-profit-margin?timespan=1year&showDataPoints=false&daysAverageString=1&show_header=true&scale=0&address=

the profitability of mining has dropped massively since June 2013 while the values of bitcoin have soared.  The miners now have a NEGATIVE 800% profitability.  Now knowing these guys aren't stupid I would tend to assume that the only entities "mining" at the moment are the ones WILLING to take a massive loss for some reason.  The only reason I can think is some entity is willing to lose a lot of money to gain control of the blockchain.  Tell me where I'm wrong because again, I'm no expert but don't see another logical explanation based on my limited knowledge of bitcoin.