[The Colonel]

Saw a video documentary on this not long ago - suggested that "the sea peoples" didn't have a fixed identity but were a mixed bag of displaced people, including those whose cities had been destroyed in raids by early sea-peoples.
Also suggested that the first sea-people raiders might have been light infantrymen, originally trained for chariot support and then made redundant in an outbreak of peace immediately before the collapse started.
Although it would be interesting to see a detailed comparison between this period and the age of migrations around the fall of Rome ... almost a millennium apart.