I don't understand how you can dismiss Craig Bellamy's winning mentality. Sure he hasn't been at the best club in the country for 2 decades. Was that down to a lack of winning mentality or not having the same talent as a youngster? Bellamy worked up through the ranks during his career and was arguably at the peak of his powers during the second half of his career. He's not had the fortune to have had Giggs' talent, where he was always going to be a regular at Old Trafford.
I would suggest that Giggs' success came down to him being an unbelievably gifted footballer. He was doing things on the pitch as a teenager that Bellamy wasn't capable of, that's a certainty. I disagreed with the comfort zone comment and agree with you that Giggs still needed to work hard at Old Trafford to keep his place. However, I reckon to suggest Giggs has more of a winning mentality than a guy who probably had to work harder in his career to climb the ladder (then got close to the top in the latter stages of his career) is nonsense.
Give me someone who strives to make themselves better and will push themselves any day of the week. Given a darting analogy, take Peter Wright. Someone who, until he made his only world final, you'd never have considered for a major tournament. He hasn't the natural talent of someone like MVG or Taylor but has been absolutely focused on what he wants from the sport and how much work he needs to put into it to get where he wants to be. He still won't make world number 1 or world champion (in my view), but it won't be for his will to win.