look at why these monarchies were aboloihed, things like communism and military dictatorships are responsible.
The point is most fallen monarchies would not have so swiftly met their demise had there been strong / vocal popular support behind them instead of widespread antipathy / apathy.
And remember that far more European monarchies were eliminated / swallowed by other monarchies than by communists and military dictators: Duchy of Mantua, Khanate of Crimea, the monarchies in and near Georgia, the Kingdom of Poland, Duchy of Kurland, the Principality of Piombino, the 2 Hohenzollern principalities, Electoral Hesse, the Kingdom of Hanover, Duchy of Nassau, Duchy of Modena & Reggio, Duchy of Parma, Kingdom of Two Sicilies, Grand Duchy of Tuscany, Kingdom of Montenegro. Only in a few cases (Georgia, Poland and Two Sicilies) was there noticeable resistance by the citizenry. And don't forget how many lesser monarchs (Leiningen, Solms, Hohenlohe, Löwenstein, Bentheim, Waldburg, Oettingen, Fürstenberg, etc.) in the final years of the Holy Roman Empire were gobbled-up by neighboring monarchies during a chaotic free-for-all of secularization and mediatization.
In the case of fallen monarchies which were not absorbed by other monarchies, the citizenry in Mexico, France (in both 1848 & 1870), Neuchâtel, Brazil, Portugal, Russia, Austria-Hungary, Ottoman Empire, Italy, Greece, and the German Empire and its 20+ subsidiary monarchies largely moved on after alternative governments were established, with relatively few shedding a tear over the deposed dynasty, or even bothering to look back.