Why/how delayed gratification?

This NY Times article (You're so Self-Controlling) discusses (and unfortunately confuses?) the difference between failure to delay gratification based on (1) a lack of self-control versus (2) a perception that the future reward is too uncertain to wait.

For instance, recent research recreated the classic marshmallow experiment done with children (the children could eat one marshmallow right away or could wait to get another one). Researchers wondered whether the choice to eat or wait was really the result of a lack of self-control, or whether the children were just unsure whether the second marshmallow would come in a timely manner. Performing a similar experiment, they found that children who believed the experimenter to be unreliable would wait only 3 minutes for the second marshmallow before giving up and giving in, whereas children who believed the experimenter to be reliable would wait as long as 10 minutes before giving up. So is it all about ascertaining the uncertainty of the future rewards? Because in the original marshmallow experiment, the researchers followed the children into young adulthood and found that the children who could wait longer tended to be more successful, which suggests that their ability to delay gratification can't just be the uncertainty of future rewards.

It's an interesting question for sociopathy because sociopaths are notoriously impulsive? Which has led some to believe that sociopaths can never plan ahead or stick to any particular plan. Taken to the extreme, this would suggest that most sociopaths wouldn't even be able to graduate grammar school, and yet some manage to become CEOs of major companies, political leaders, or hit other high levels of skill or achievement. Personally speaking, I have managed to perform very well at certain long term tasks, including excelling in school, at work, and managing to fully fund my retirement. How? Maybe the answer lies in what we mean by "impulsive" and what relationship impulsivity has with how we view will-power. From the NY Times article:

[T]he ability to delay gratification has traditionally been seen in large part as an issue of willpower: Do you have what it takes to wait it out, to choose a later — and, presumably, better — reward over an immediate, though not quite as good one? Can you forgo a brownie in service of the larger reward of losing weight, give up ready cash in favor of a later investment payoff? The immediate option is hot; you can taste it, smell it, feel it. The long-term choice is far cooler; it’s hard to picture it with quite as much color or power.

In psychological terms, the difference is typically seen as a dual-system trade-off: On one hand, you have the deliberative, reflective, cool system; on the other, the intuitive, reflexive, hot system. The less self-control you have, the further off and cooler the future becomes and the hotter the immediate present grows. Brownie? Yum.

But if a sociopath's rage tends to be cold-hearted rather than hot-headed, could it be that sociopaths also respond to different stimuli for impulse control than normal people do? Perhaps that they both manifest an unusual degree of impulsivity in some aspects of their life and amazing self-control in others? Maybe sociopaths feel cooler about things that often seem hot to other people. Or maybe it's because we can take future events and make them seem hotter? I feel like that is at least sometimes true of me, that I can imagine my future self vividly enough that I feel some of the pleasure of the delayed gratification in that moment that I'm delaying it.