Theres no real money in Serie A anymore, we only have four at a push 6 famous teams, la liga has about 10-12 and the UK has about 15 (to the african audience its about 50) famous teams.
When serie a gets some european titles the money will start coming back, seria hasnt won anything since 06-07 and before that 2003 iirc.
I'm not sure what you mean by famous. Napoli is a far more famous club than Villarreal, for instance.
Juve
Milan
Inter
Fiorentina
Roma
Lazio
Napoli
Parma
All of them are pretty famous for one reason or another over the past decade, winning at least one competition. Sampdoria had glory years in the late 80's/early 90's. So perhaps they wouldn't be as famous as the others to new football fans.
Barca
Real
Valencia
Sevilla
Depor
Villarreal
Atletico Madrid
Real Zaragoza
Espanyol
Some of these clubs don't match the likes of Lazio in terms of fame over the past decade, basically everyone below Villarreal in that list. So I wouldn't really say that La Liga has more famous teams, even if the subject is five years old. Espanyol would be no more known to someone like that than Parma.
It all depends on what people watch, and if some folks think a Portsmouth is more famous than Napoli, that's just typical BS and I don't respect such fans. They know nothing about the game.