Bruce Lee's departure from Hollywood has long been the subject of legends. One such legend suggests that Bruce Lee left Hollywood for Hong Kong after he lost out on the lead role in the TV series Kung Fu. However, this turns out to be false.
Bruce Lee did pitch a show called The Warrior about a martial artist in the Old West, but Kung Fu was developed separately and predated his show. Although he may not have been treated completely fairly, it was not the reason he left Hollywood.
Another legend suggests that Fred Weintraub, an executive vice president at Warner Bros., recommended that Bruce Lee move to Hong Kong after his role on Kung Fu did not work out. However, this is also false.
In reality, Weintraub met with Lee about a film version of Kung Fu in 1970. When that didn't work out, he advised Lee to pursue a film career in Hong Kong. Lee visited Hong Kong in 1970 and discovered that he was already a major celebrity there. He then worked out a deal with Golden Harvest Studios and filmed his first Hong Kong film, The Big Boss, in 1971.
Therefore, Lee's disappointment over not being cast in Kung Fu could not have been the reason behind his decision to move to Hong Kong, as he had already moved there by that time.
In conclusion, Bruce Lee's departure from Hollywood was not directly linked to his involvement with Kung Fu.