Psychology 101 will tell you that many of the problems we face as adults began in our childhood.

Anakin Skywalker's childhood was a miserable one. No doubt he had good times: loving moments with his mother, fun times with his friends, but for the most part his life was one of slavery. I would guess that Anakin probably suffered some abuse (verbal and physical) at the claws of Watto. A boy can run, but Watto could fly.

Anakin probably accepted his slavery the way most of us accept that trees have green leaves. No, he wasn't happy about it, but it was part of the landscape of his life. So where did the bulk of the angry, frustration, and hate come from?...

A disabled pod racer known as Sebulba. OK, he looks disabled to me.

Sebulba taught him to mistrust the Jedi and take everything they did in his training the wrong way. He did this by reminding Anakin that he was a slave. If that didn't work, he might have brought up that he had never finished a race. Or perhaps he simply brought up his age. An adult Anakin would take these things and project them on someone. The Jedi were training him. It is a humbled thing to be trained. Most people are not properly trained on their jobs because they want to pretend like the understand, rather than ask for help. This may have felt to Anakin like Sebulba saying he wasn't good enough.

Furthermore, many of the Jedi were non-human. Think about the non-humans in Anakin's life: Watto, Sebulba, and early on, Gardula. These were negative experiences with other intelligent beings. Anakin's first good experience with a non-human (that we are certain of) was with Jar Jar, and then it was a being who was clumsy and perhaps not up to Anakin's standards of an adult intelligent being. Therefore, Anakin may have grown to mistrust the Jedi because many were non-human and he was leery of a human/non-human union. Perhaps Yoda was the head because he pushed others down...like Sebulba and Watto had pushed him down?

There are two kinds of evil, I believe. One is like Sebulba: obvious. He planted devices in other racers pods so they would crush. He ridiculed a little boy who, until Qui-Gon came along, never had a chance to win the race anyway.

I believe Anakin understood how to spot that kind of evil. It was apparent in Darth Maul and apparent in Count Dooku because he was an open Separtist.

However, Sebulba's influence, I believe, extended to what he was not. The second kind of evil is subtle. Palpatine was this kind of evil. Anakin had never known this sort before. When finally confronted him it, when Palpatine revealed he was the Sith, it was too late. Anakin was confused. I think that in Palpatine Anakin believed he had found his Qui-Gon replacement.

So the local bully's influence went along way to destroy (at least for about twenty-six years) a galaxy.