You don't know that he has a pair. Unless he's got KK or AA, you are AT WORST a coin flip, and at best you are hugely dominating a hand like AQ or AJ (with only 8 BB's left, he is definitely pushing those hands UTG, probably even AT-A8, depends on the player). The fact that you are getting a big overlay from the blinds only makes the call easier. Now is the best time to be taking flips. With blinds this high, skill matters a lot less and luck and good cards matter a lot more. The difference between busting now and getting blinded away a couple of orbits from now is miniscule compared to the big money into which a large stack could carry you.