Yes. He wanted to be regarded as the best player ever and knew that he might lose so running away would make the match ambiguous.
Was Fischer afraid of Karpov
No to Karpov.
Yes to losing in general. I think he knew that eventually someone would beat him, and he didn't want that. If not Karpov, then Kasparov. If not Kasparov, then Kramnick. The point is that he would have either been beaten or forced to step down eventually--he chose to do so before anyone could point and say "Fischer backed out because he was afraid of Karpov." But Fischer was very arrogant--I don't think he would ever admit to being afraid of anyone--he was just afraid of the unknown.
No. I agree with chessmicky, it had nothing to do with Karpov. Fischer had reached the top, and all he could do was try and keep his place there. It's really no wonder he self-destructed.
Yes he was afraid of Karpov. 2-3 years later he stayed with Polgar sisters in Hungary and they would also beat Fischer more often. If Fischer would have stayed till Kasparov's arrival then Kaspy would have crushed him.
They never forced any challenger to win with a margin of two points, which is what Fischer demanded when he refused to play unless Karpov had to score 10-8 to become World Champion.
But I don't think Fischer was afraid of Karpov specifically, I think he was afraid of playing chess in general and that this was why he had quit chess three years earlier and probably also why he came with all these demands, as an excuse not to have to play.
To comment on a chess great without having the first hand knowledge of the circumstances of his quitting chess is both unfortunate and disgrace.

Fischer could sleep with vampires, can't blame him for retiring way he did, Karpov would have bored his pants off, took him another 19 years to even reach Fischers outdated rating, playing hundreds of games more than Fischer.

They never forced any challenger to win with a margin of two points, which is what Fischer demanded when he refused to play unless Karpov had to score 10-8 to become World Champion.
But I don't think Fischer was afraid of Karpov specifically, I think he was afraid of playing chess in general and that this was why he had quit chess three years earlier and probably also why he came with all these demands, as an excuse not to have to play.
Two points seems a lot.
Except that on a 24-game match were draws count, Fischer would wipe out everyone- Karpov and even Kasparov.
It seems that everyone seems to forget that Fischer became world champion even though he was down 0-2 in a 24-game match.
The thing that everyone seems to forget is that once the champion gets a one-point lead and draws count, the challenger would have to take risks to avoid a draw.
The first Karpov-Kasparov match demonstrates how a 24-game match would have made Karpov champion. For after winning 4-0 there were 17 more draws!!!
Fischer asked for draws not to be counted.
"Fischer insisted that the match be the first to ten wins (draws not counting), but that the champion would retain the crown if the score was tied 9–9" (from the wiki on Karpov).

He must have been afraid of Karpov, just like he feared all the Russians that came before him.
He must have been mental to play against them all!
Still though, vampires ran a mile anytime Fischer was near.

Isn't there already a 50+ page thread on this topic?
Oh, I see, this a just another troll thread and an introduction to the latest sockpuppet, ostensibly from France.

yeres post on vote amazing thankyou for posting was unaware
just popping by to say no stop picking on bobby fischer love his chess then read your post had to agree
Yes/no vote.