Semantic issue here: there are TWO factors here, both worded the same.
Interpretation 1:
The casual fans are the majority of all fans (unfortunately), and they need the stars to stay interested.
The casual fans are the ones that need the stars, and if they have the stars, they stay interested.
Interpretation 2:
The casual fans are the majority of all fans (unfortunately), and they need the stars to stay interested.
The casual fans watch, but they need the stars to be interested in the race otherwise they will swiftly get bored.
The casual fans may be suckered in by the presence of stars, but they will swiftly turn away again if they detect that the stars are just collecting a paycheck or phoning it in. You credit the casual fans with very little intelligence and suggest that they cannot be enticed by exciting racing, only by the presence of big draw names, but that they will watch those big draw names even if it's tedious as all hell. Let us also consider a few other things:
- because of the timezone differences, it is entirely feasible for an audience to watch both races; they are not mutually exclusive.
- the Giro is, first and foremost, an Italian race. It is Italian companies that stump up the money for it. It was rather provincial at times in the last two decades, but it didn't decrease in value. And as far as Italy is concerned, who cares if Cancellara, Boonen and Cavendish are in California? It's the GIRO! All their big names are there, and the history and status of the race is that high in Italy and Europe that they will continue to draw big names and sponsorship money.
- the Giro does not see itself as subservient to or less than the Tour, nor does Italy as a whole see their race this way. It does not see itself as a Tour warmup race, so why should it want Tour riders to come without risking their Tour chances? As far as they're concerned, their race is as important, so it should be as hard - if not harder.
- the Giro has enough fans in Europe and abroad that it is in the driving seat here. It is established, it has a rabid local following, and it is able to afford to run at its present level. The coverage is more professional than California, the scenery is more attractive, the racing is better, and they have enough of a fanbase to maintain it. Not everything is about chasing the dollar.
The Giro is not under any threat because of California, any more than it was under any threat because of Catalunya (which is aeons old and was ProTour, therefore took more big teams than California does). The Cancellaras, Schlecks and Boonens of this world wouldn't ride the Giro anyway, immediately after their primary goals (spring classics) and before they build up to their second primary goals (the Tour in most cases).
The Giro isn't "losing stars" to California. Is a top 10 of Basso, Arroyo, Nibali, Scarponi, Evans, Vinokourov, Porte, Sastre, Pinotti, Kiserlovski
really a weaker top 10 than a top 10 of Menchov, di Luca, Pellizotti, Sastre, Basso, Leipheimer, Garzelli, Rogers, Valjavec and Bruseghin? Bearing in mind that the 2010 Giro also saw names with GT top 10s like Tondó, Garzelli, Pozzovivo, Bruseghin and Vande Velde drop out due to injury?
No, California does little more than fill a hole in the calendar for a few big names who would normally be resting at the time or maybe doing a relatively minor race like the Bayern Rundfahrt. The Giro is not under threat from California in any way, shape or form, and will not be unless things change majorly.