It has been widely shown that the dark side is the quick and easy path to power, and that many fall because the lure of that power is too great for them to resist.
I accept that power comes faster and more easily when one gives in to the dark. My argument was that I think a very large portion of dark Jedi turn dark because it's less restrictive. Once they take the first few steps, the power pulls them in further. Look at Anakin. He fell to the dark side to begin with, because the Jedi had too many restrictions. If the Jedi weren't so heavy handed when it came to love and family, and they actually learned to cope with their emotions, as opposed to just trying to control, or shut them out, Anakin may not have fallen.
The Sith and most dark Jedi let their emotions, mostly hate, and anger and the like, run free. I think if force users learned how to handle their emotions, both good and bad, in a healthy way they could be stronger.
The Potentium, Imperial Knights, Gray Jedi (and I mean true gray, not "I just can't make up my mind" types), and Voss mystics are a great example.