In an industry where players are paid extraordinary amounts of money, Ronaldo's pay deal with Saudi Arabia was astronomical. The footballer was reportedly paid $200m (£152m) a year - or more than half a million dollars a day.
Then in June this year, he signed a new two-year deal for a reported total of $400m (£300m) and became football's first billionaire player, according to Bloomberg, with a net worth of $1.4bn.
That's a lot of money for a 40-year-old footballer in the twilight of his career.
But, according to Sanam Vakil, director of the Middle East and North Africa programme at Chatham House, Saudi Arabia has "invested heavily in high profile events and individuals to put the kingdom on the map" in terms of sports and tourism in its quest for modernism.
Ronaldo has referred to Prince Mohammed as "our boss" in an interview with broadcaster Piers Morgan.
Earlier this month, he appeared at a Ministry of Tourism event in Riyadh where he talked up the kingdom's development projects and his hopes for the 2034 FIFA World Cup being held in Saudi Arabia.
As for meeting Trump, Vakil says: "The US president likes shiny things and Ronaldo is a shiny thing."
Though the footballer has loftier ambitions for the meeting in Washington - world peace.
In July, European Council president Antonio Costa handed Trump a Portugal jersey signed by Ronaldo which read: "To president Donald J. Trump, Playing for Peace."
He told Morgan: "I hope to sit down with him someday because he's one of those people I really like.
"I think he can make things happen and I respect people like that."