. Again, I think his life style and attitude got him a lot of extra fame - if you look at the other Jacksons whose music were mediocre at best, it didn't stop them being huge in the US either while they barely registered outside of the US.
The only adult Jackson besides Michael that was huge in the US was Janet. Tito, Jermaine, LaToya and whatever other random Jackson sure as hell weren't huge here. In fact the only things huge about them were the huge career flops they produced. And I wouldn't say that Janet Jackson's album's "barely registered" outside the US. Not amazingly popular , but still enough to have her albums peak with a top 10 position of many album charts outside the US.