It's international waters, but China has other ideas. Now that encroachment is getting too close for comfort.
You seem to have the misconception that if the PAP regime had hypothetically saved a certain sum of money, it would have been channeled towards more productive or practical uses, or it trickles down to benefit the the masses.
Clearly, you have forgotten what kind of country we live in.
Even if you sincerely consider this as a wastage of public money, it's peanuts compared to the wastage in other areas.