I don’t think it’s at all clear that the OP meant D1 by “first class”. Considering (s)he mentioned reading TPG and the blogs are full of aspirational first class trips on other airlines (although mostly credit card sign up links) it’s entirely reasonable to think that that is what the OP was after, especially since t says “first class”. It seems anyone who knows damn well that the OP meant Business is making a mighty big assumption.

Of course it’s also possible the OP meant domestic first which with that amount of miles they should be in good shape for now at least.

I suspect people feel the need to correct the first class issue to try to prevent umpteen new threads from people who have transferred their miles to DL and then can only redeem for C.