7. Mark Henry
These days, Mark Henry is a WWE Hall of Famer and a one-time World Heavyweight Champion beloved for his ass-kicking Hall of Pain days. But for a spell there, Vince McMahon must have had a huge sense of buyer's remorse over the initial contract he'd signed the World's Most Strongest Man to.
Having competed at the 1996 Olympic Games, Henry was snapped up by the then-WWF. An established, successful athlete, making the jump to professional wrestling? That's something that's been commonplace in WWE and across the wrestling business for decades. While McMahon taking a chance on Mark Henry was no major surprise, what was surprising was the contract given to the hoss-like strong rookie.
In an unprecedented move, Henry was signed to a whopping ten-year deal worth a guaranteed $250,000 per year at a time when guaranteed money wasn't commonplace in the WWF. For a rookie with zero wrestling experience, this was a truly huge deal - and one that irked many of those on the WWF roster at the time.
What made this worse for McMahon for a spell, is that Mark Henry just didn't click with the business for several years. Initially too green for the role he was put in, it looked like taking such a punt on the Olympian was a foolish move from the company. Still, they were tied in for ten years, regardless.
Fortunately, Henry finally found his groove and would go on to become one of the modern-day great powerhouse performers.