Check it out how many celebrities do have second (3rd, 4th) homes in or around Monaco on this southern coastline of France! How many are visiting on a regular basis for summer holidays there that includes a visit -to be seen- during the race days. These guys are booking five and six star hotels and don't care about rates.
But think about it, do they come in thousands? Definitely not they are actually a minority.
As a result many of that specific group of fans, may give Singapore a miss, maybe not in the first year since it's a new venue and the first F1 night race ever!