Why are Nigerian players missing from list of 50 richest players on the planet?

As the world’s biggest and most influential football website Goal.com released its highly anticipated list of the wealthiest footballers alive, many Nigerians were surprised to find that none of their countrymen had made the list. While Nigerian businessman Aliko Dangote was listed among the top 50 billionaires in the world by Forbes a few days back, no Nigerian footballers made the list of the elite of their sport after the country recently won the Africa Cup of Nations.

The Goal Rich List was arrived at after measuring “only identifiable assets including salaries, length of contract, bonuses, endorsement and sponsorship deals, accounts filed at Companies House, properties and other business interests” of the players who must be Fifa registered professional players , or registered players currently without a club, but who are actively looking to sign for a professional club.
Interestingly, Africa had four representatives in the coveted Goal Rich List with Samuel Etoo of Cameroon leading the charge. The Anzhi Makachkala striker is listed as having 12.3 billion naira (£52m). Etoo is listed number six in the global list.
The next African on the list is Cote D’Ivoire striker Didier Drogba who has 5.9bn naira (£25m). Drogba now plays club football at Galatasaray in Turkey after he led Chelsea to the Uefa Champions League trophy last season. He is in 24^th position on the rich list.
Both Michael Essien and Yaya Toure are the other Africans on the list with 3.9bn naira each (£16.5m). They are listed in 48^th and 49^th positions. Essien who is on loan at Real Madrid from Chelsea has not played for Ghana since 2011.
Ivorian Toure is reigning African footballer of the year.
The lack of Nigerians on the list could be cause for concern but columnist Calvin Emeka Onwuka said the reason is simple: “[Nigeria has] not produced a top player in the last 12 years.” Or perhaps they have not mastered the science of marketing themselves properly?
Thirty seven year-old Englishman David Beckham is the richest footballer on the planet with 41.5bn naira (£175m). Beckham recently moved to French giants Paris Saint Germain where his five months salary of 80m naira (£3.4m) is to be donated to charity. The bulk of his earnings come from outside football.
Four-time Fifa Ballon D’Or winner Lionel Messi is the second richest footballer with 27.2bn naira (£115.5m). The Barcelona striker has broken several records in club football that many regard him as the best footballer to ever play the game.
His rival at club level, Real Madrid’s Cristiano Ronaldo is listed third on the Goal Rich List with 26.5bn naira (£112m). The Portuguese is widely seen as one of the most complete players in the game with the ability to score goals and also create them while also lending a hand in defence.
Another Real Madrid player is Kaka who comes in at number four with 15.6bn naira (£66.5m). Even though he spends more time on the bench than on the pitch these days, the Brazilian is still in the elite zone in terms of monetary rewards.
His compatriot and fading star Ronaldinho is in fifth place with 14.9bn naira (£63m). Even though he moved back to Brazil after brilliant stints in Europe, the Atletico Mineiro midfielder maintains his billing among the top paid stars in the game.
Noteworthy is the fact that out of the top five wealthiest footballers, only Beckham has not won the Ballon D’Or, the biggest individual prize in world football given to the best footballer annually by Fifa.
All the players in the top five have played or currently play in Spain for either Real Madrid or Barcelona and three of them are from South America.
What is responsible for Nigerian players not reaching the top 50 wealthiest players list?