Ronaldo scored 101 goals in a Juventus shirt, crowned with two league titles, one Coppa Italia and two Supercoppe. As Luigi Garlando wrote in La Gazzetta dello Sport: “In three years, CR7 amassed the numbers of a normal human’s entire career.”
Juventus are currently doing a squad re-build, and Ronaldo at this stage of his career is the cherry on top of a ready made cake, not the player you need to build your team around, especially with only a year left on his contract. This is why a short deal at City/United was quite enticing for both clubs. He guarantees goals, trophies and success. He demands it. Who doesn't want a bit of that?