You know, breaking up with someone does not mean you made a mistake, but that it simply was not working. We can choose to look at it negatively, or see whatever he brought in her life that makes her happy.
I think there's a distinct narrative here being forced by fans. You guys are worried she's getting used, but in truth, Britney will rarely meet someone as successful as her and have a match (try to find the 1% in the 1%, basically). It could happen, but then, who's to say it's not a power dynamic and whoever she meets would like to have the upper hand? Seeing she's a very grounded person, she probably was looking for someone as grounded as her, and maybe Sam is that person. Even if they were to break up in 5-10 years, that doesn't mean Sam didn't bring her happiness sometime in her life. Hell, if anything, he was present in one of her most decisive moments as a person.