I think all is about right except for your very first statement — Prohibition began when the 18th Amendment took effect in 1920. While Kennedy had enjoyed some modest financial success to date, His first major fortune was made in the 1920s, during Prohibition — although most of his fortune (as you noted) came first from his shady stock market dealings, and later from his investments in Hollywood, oil etc.
re: Prohibition and the 1920s
I’m pretty sure his major fortunes were made first with stock market manipulations and then as he re-invested funds in Hollywood, oil, and real estate.
Not sure he ever made much money from alchol before the 1930s, once it had become legal again. The bootlegging has been a rumor, maybe a “legend” — but I don’t know of anything which has emerged about his life in the 1920s that suggests he was in the bootlegging biz. Certainly he became a major successful importer of whiskey and gin in the 1930s, but for all his other faults I’m not sure that the “bootlegger” label has really been pinned on him with any evidence (although maybe he just covered his tracks well since it was illegal).
Joseph P. Kennedy
Father of President Kennedy, banker, financier, diplomat. Chairman, Securities and Exchange Commission (1934-1937); Chairman, Maritime Commission (1937); Ambassador to Great Britain (1938-1940).
http://www.jfklibrary.org/Historical+Resources/Archives/Archives+and+Manuscripts/Kennedy.Joseph+P
Joseph P. Kennedy was the ambitious son of a prosperous Boston saloon keeper and ward boss. He married the mayor’s daughter, went to Harvard, and generally made the most of his ample connections and talent. He ran a bank (admittedly two-bit) at 25, and was number-two man at a shipyard with more than 2,000 workers during World War I. At 30 he became a stockbroker and made a fortune through insider trading and stock manipulation. He was a master of the stock pool, a then-legal stunt in which a few traders conspired to inflate a stock’s price, selling out just before the bubble burst.
Kennedy may also have traded in illegal booze, although the evidence is circumstantial. His father had been in the liquor business before Prohibition, and Joe himself got into it (publicly, that is) immediately after repeal. Some believe the family business simply went underground during the dry years. He may have been strictly a nickle-and-dimer; Harvard classmates say he supplied the illicit booze for alumni events.
But there might have been more to it than that. In 1973 mob boss Frank Costello said he and Kennedy had been bootlegging partners. Other underworld figures have also claimed Joe was in pretty deep. At least one writer (Davis, 1984) thinks bootlegging enabled Joe to earn his initial financial stake, but that’s hard to believe; he had plenty of chances to make money more or less legally.
http://www.straightdope.com/columns/read/716/what-is-the-true-source-of-the-kennedy-familys-wealth