After they won the 1968 European Cup, there seemed to be a load of cockney reds in my local school all of a sudden.
They have a certain 'history' and with recent success and global television coverage, it's no wonder there are people in China and New Zealand buying Man Utd tat online.
In the UK there are a disproportionate number of Man Utd and Liverpool fans of Asian ethnicity because their parents didnt go to games because of 'hooliganism', they could only watch TV and they were the two most successful clubs of the late 60s and 70s up until the 90s. This 'allegiance' was passed down to their next generation.
They also use aggressive marketing, worldwide pre season tours as do the other 'top four'. They are (or were) the biggest supported club in the World which is why the Glazier parasites leeched onto it.
Chelsea is essentially the Word of God being spread through out the World whereas ManUtd is some hideous Aids like virus that infects weakened indivuiduals, leading to paralysis, incessant masturbation, and eventually a tedious death.