I am unsure of the generality of the sources here, but the author — Jay Bahadur — is writing a book on the topic and at the very least his investigation sounds serious:
The figures debunk the myth that piracy turns the average Somali teenager into a millionaire overnight. Those at the bottom of the pyramid barely made what is considered a living wage in the western world. Each holder would have spent roughly two-thirds of his time, or 1,150 hours, on board the Victoria during its 72 days at Eyl, earning an hourly wage of $10.43. The head chef and sous-chef would have earned $11.57 and $5.21 an hour, respectively.
Even the higher payout earned by the attackers seems much less appealing when one considers the risks involved: the moment he stepped into a pirate skiff, an attacker accepted a 1-2 per cent chance of being killed, a 0.5-1 per cent chance of being wounded and a 5-6 per cent chance of being captured and jailed abroad. By comparison, the deadliest civilian occupation in the US, that of the king-crab fisherman, has an on-the-job fatality rate of about 400 per 100,000, or 0.4 per cent.
As in any pyramid scheme, the clear winner was the man on the top. Computer [a man's name] was responsible for supplying start-up capital worth roughly $40,000, which went towards the attack boat, outboard motors, weapons, food and fuel. For this investment he received half of the total ransom, or $900,000. After subtracting the operating expenses of $230,000 that the group incurred during the Victoria’s captivity in Eyl, Computer’s return on investment would have been an enviable 1,600 per cent.
There is a very good chart on the right-hand side bar of the article.