MisterShark, once you stunt combo during the first few turns and you resolve Mana Drain or top deck some Acceleration, you can win in a few turns. Once you force Combo into more of a control match, you have the upperhand.
I'm going to hack your quote to illustrate the flawed nature of your question:
What combo decks allow one to get up to any kind of potential mana to effectively cast Exalted and flip it, and swing 5 times before going off and sealing your fate?
What combo decks allow one to get up to any kind of potential mana to effectively cast Intuition (or TFK) and Mindslavers activation cost before going off and sealing your fate?
What combo decks allow one to get up to any kind of potential mana to effectively cast Future Sight and Top before going off and sealing your fate?
What combo decks allow one to get up to any kind of potential mana to effectively cast Gifts Ungiven, Recoup into Will, then Belcher before going off and sealing your fate?
Lots of win conditions are mana intensive. We're not always trying to race combo, they key is to keep them away from the ability to combo you out. That's why you fill your hand up Scryings so you can answer with Drains, Forces, Duress, and Tutor/Wish for Mind Twist often.
Also, despite all that life-loss, it's not risky because this is type 1. If you're in a position where your life total is going to matter, it's because you failed to properly control the game.
I'm probably going to leave this thread alone until part two gets put up. The questions posted here can either be answered in part 2 and part 3.