In short, a key part to winning big in NLHE is tending to play big pots with your strongest hands and tending to play small/medium pots with lukewarm and vulnerable hands. Without strong reads, the implieds odds on sucking out are probably better than you'd think. Hence, with lots of money behind it can be correct to give a card with a vulnerable hand if you're not going to pay-off more than pot and are likely to induce a bluff.