I've found that the learning to avoid the opinions of the latter type of person allows you to focus on your goals while feeding off the positive feedback of the facilitators allows you to achieve your goals. That said, it is important to surround yourself with both types of people, the facilitators may be compelled to provide advice but they can also out of empathy for the time and effort you've expended in your pursuits, to omit a level of honesty that may be needed in order to turn your ship so to speak if it seems you are headed inexorably toward an iceberg. On the opposite end , the destroyers can serve as a form of positive motivation toward achieving your goals. In order to make use of them you must be able to feed off evil, not everyone is able to take clearly negative or demeaning comments and turn them into sources of positive motivation but when others wish you ill you should focus on the germ of truth that usually attends such talk to eradicate it. By doing so you clear yourself to exceed your expectations and prove the destroyer wrong in one go. I've always prided myself on my ability to take a negative comment (even one that is not necessarily intended to be malicious) and use it, feed off of it. A relentlessly competitive spirit allows you to set up competitions between yourself and whomever it is you perceive has issued a challenge. I've always perceived challanges from others , even when no explicit challenge was made, this level of paranoia allowed me to achieve several goals I've set for myself. When I was in grade school, the challenge set by my peers was motivation for my studies once I came home. I remember studying for hours every night, commiting to memory every word that was written on the black board of my social studies class room just so that I could recite it, word for word the next day. I got a thrill of achievement from that act that I can't explain, since then I've tried to recreate that thrill by picking up challenges put forward by others. I must admit to a level of paranoia in this tendency, when I go running I feel immediately challenged by any runner that comes abreast of me, their attempt to pass in their own pace modifies my own. I take it as a secret inner challenge and use that to accelerate my performance for that session. If that person had not come, I would have been less likely to increase my pace for my own inner reasons. I've sought to simulate this challenge by keeping my times from previous runs and consulting that during the run. Self measurement is a key way to pace your present achievement against your past and keep track to achieving your goals. Without that self measurement you tend to get lost in mediocre performance that detracts you from achieving your goals in the timeline that you set. In the last 6 years, the challenge of designing a distributed web framework and applications to run on it has put me on a playing field where all my competitors are non local. My challenges came from the other founders, technologists and entrepreneurs that have struck out to try and solve problems that I also attempted to solve. In so doing inevitably a clash of ego's leads to arguments. An ex coworker of mine who I've kept in contact with for the last 7 years or so has served his purpose as a constant source of challenge for me, though he may not be aware of this, his words have motivated me to prove him wrong on many of the malicious statements he's made concerning my endeavor. Some people would question why I keep him in my circle of "friends" but he has been invaluable in allowing me to wake up periodically and re-assess what I am doing and why. These sessions have allowed me to redouble my efforts, now it is likely I would have done this anyway but the motivation from the perceived challenge has sharpened my focus. I have people who I can confide in and get good news on what I am doing but those people are afraid to hurt me if they feel what they say can, my friends are the ones who aren't afraid to hurt me when they state their opinion. I have to still divine weather their statement is one of malicious or caring intent but the act of doing so still focuses my mind to prove them wrong either way. Also in these experiences I learn to criticize others always with a solution to accompany the criticism. The old saying that if you have nothing good to say, say nothing is one we all should learn to adhere to but this is not to say hide what you perceive as the truth from those who know. It is to say, present the truth in a dispassionate and caring way and not an openly malicious one.
You never know when the negative or intentionally malicious comment you give someone leads them to a path of ruin, so you should always choose your words carefully. Not everyone is as resilient to challenge as you may be, not every one is as stubborn in the face of adversity, keep this in mind when interacting with others. Also it is important to fully immerse yourself in the perspective of others before you can say anything intelligent about what they are doing, don't assume that a two minute introduction is enough to make you an expert in something that someone else has been working on for years. This belies a level of arrogance , conceit and impulsiveness that can be detrimental to yourself and to those with whome you interact.
So feeding off evil, is good...in fact imperative to achieve your goals...but don't spread it.