#3 Alberto Del Rio
Alberto Del Rio is a second-generation wrestler from Mexico, and WWE pushed him immediately after his debut. He was a part of a World Heavyweight Championship match within a few months after his debut. Del Rio even won his inaugural Royal Rumble match in 2011.
The Mexican Aristocrat chose to fight Edge at WrestleMania 27 for the World Heavyweight Championship. However, similar to Sheamus and Daniel Bryan, the pair had to kick off Wrestlemania 27. Del Rio would never get a chance to main event WrestleMania, and since he is not in WWE, there are only little chances of him headlining the show of shows.
#2 Vince McMahon
Looking back to the history, it is tough to believe Vince McMahon won a Royal Rumble match. This fact is made even more bizarre by the fact that the CEO of WWE started at number 2 in the match. McMahon was the 1999 Royal Rumble winner - a time when WWE was at an all-time high.
Even though he could insert himself in every single WrestleMania main event, it would be stupid if not for any strong storyline reasons. With him being 73 years old and far from peak physicality, McMahon may not headline any WrestleManias.