By moving from McLaren to Mercedes, Lewis Hamilton is taking a gamble that could define his career in Formula One.
McLaren is a team that consistently wins races. Mercedes believes it can become such a team, but has yet to prove that on the track.
If Mercedes is right, Hamilton will have made the right move. If Mercedes is wrong, Hamilton will end up in F1's no-man's land, trailing other drivers who are winning the world titles he so badly wants for himself. ( Also read: McLaren chief says Hamilton making a mistake)
One, but not the only, measure of a great F1 driver is whether he can replicate success with different teams.
Michael Schumacher did that. His first two world titles, in 1994 and 1995, came with Benetton. Then he, too, took a gamble, moving to Ferrari, a team that hadn't produced a world champion since Jody Scheckter in 1979.
With perseverance, that paid off handsomely. Five consecutive world titles in bright Italian red from 2000-2004 saw Schumacher overtake Juan Manuel Fangio as most successful driver.
Hamilton was F1's youngest and first black champion when he won his only world title, with McLaren in 2008. His dazzling speed, steely, borderline aggressive, driving style, and his huge self-belief entitle Hamilton to think that he should have won more. Had McLaren done better in the past four years and given Hamilton cars that could win, not just races but world titles, too, then maybe Mercedes' offer to move wouldn't have been so tempting.
Then again, maybe not. Maybe this or a move elsewhere was always going to happen, eventually. In leaving the only F1 team he's raced for, one which nurtured him since his teens, Hamilton is moving out of his comfort zone. And that's healthy. (Also read: Feature - Hamilton's switch changes F1 landscape)
Since he raced karts as a boy, Hamilton wanted to drive for the British outfit with 46 years in F1. The team's website recounts how, at age 10, he told McLaren boss Ron Dennis, "I'm going to drive for you one day."
To leave familiar surroundings behind takes courage. It shows ambition. It shows that Hamilton is prepared to test himself in a new environment, with new colleagues. Many of us do that in our professional careers. And many will agree that such leaps, to new jobs or to new postings, help us learn and grow. The same will surely be true for Hamilton.
Money will have played a role, too, although only Hamilton will know exactly how much that weighed on his decision. McLaren drivers have what are known in the business as "body and soul" contracts - allowing them limited opportunities to sign endorsement deals of their own. They are paid handsomely. Hamilton's replacement, the exciting 22-year-old Mexican Sergio Perez, will get a basic wage of $32 million over three years, plus win bonuses. Hamilton may have gotten between two and three times that had he stayed at McLaren.
Mercedes, one imagines, must have offered Hamilton an equivalent salary or more. But he will also have greater leeway to sign his own potentially lucrative endorsement deals on the side - which, no doubt, will please his management team that also looks after the likes of David Beckham, tennis player Andy Murray and showbiz stars.
But it's hard to imagine that money would have been the only factor for a driver who takes it so personally when he doesn't win.
To woo him, Mercedes will have pointed to the work it has done since it returned to F1 in 2010 to try to catch up with McLaren, Red Bull and Ferrari at the front of the pack.
That includes last year's appointments of Aldo Costa from Ferrari as the engineering director, overseeing car design and development, and Geoffrey Willis, a veteran engineer previously the technical director at Red Bull, to take charge of aerodynamics and other areas.
They report to Bob Bell, previously with Renault, who brought his three decades of experience in motorsport to Mercedes in April 2011. In short, Mercedes could show Hamilton that it has assembled a crack engineering team - vital in a sport where success is so dependent on having not just a reliable car but one of the quickest, too.
F1 is switching to smaller turbocharged 1.6 liter V6 engines from 2014, from the 2.4 liter V8s used now. That's a significant change and challenge for all teams and their engineers. Mercedes manufactures engines. If its new V6 proves better than Ferrari's and Renault's then its cars could, at least in theory, have an advantage over rivals that use engines from those manufacturers.
But that is still an "if." How big an if won't become clear until 2014. McLaren gets its engines from Mercedes. Over the decades, it has survived and adapted to numerous changes in F1 rules and technology but continued to make cars that win races.
In 52 races since returning to F1, Mercedes has won just once - the Chinese Grand Prix this April. McLaren has had 16 wins and 45 podiums in that time, but no world title for Hamilton or his teammate, Jenson Button.
At age 27, Hamilton is severing the apron strings with McLaren, the team that raised him. Perhaps he'll be wealthier for it. But, for his racing career, the challenge for him and for Mercedes is to make sure that he doesn't regret leaving home.