If people speak about Monaco it makes me laugh each time: Monaco is very expensive. The housing is crap (small for the "affordable" ones, piled upon in a small area, expensive) There is no real beach, Larvotto is what comes closest to a real beach. No parking place for cars. Food and drinks are insane priced. In summer a flood of tourists, in winter completely dead. It looks like a "m'as-tu vu" place where all people go who want to be seen there as it shows how famous or rich they are. Artificial style of life. Saint-Tropez is far nicer. I live in far better conditions than these billionaires in the same area (more or less). Almost on the border of the sea, with seaviews from all rooms and a living space that is bigger than 95% of all housing in Monaco. And all this for a fraction of the price. People who never were in Monaco see it as they think it is in their fantasy.
Yes, Monaco is expensive, but you don't go there to save money. One of the main attractions of Monaco are its casinos. A lot of people go there to gamble. Isn't Monaco the European Las Vegas? In my opinion it is. The most beautiful European casinos are there.
The people who visit it, don't think that it is an expensive city. You go there with the purpose to spend money, not to save them. If you want to save, you should better stay at home.
Well, if one plans to move to Monaco for tax reasons, they expect to have saved money at the end of their stay there, hence they care about costs - as well as quality of life for long term stays. Imo it´s OK for wealthy older folks, there doesn´t seem to have a whole lot to do with kids. Schools are probably good and there´s a very decently priced International School there, but for some reason the royal family seems to prefer to send their kids overseas (heard about several of them studying in an international school downtown Paris)