When someone says "X", and provides a source for their position, saying "no, Y" with no source, evidence, or even argument is rightly viewed as a very weak reply. Saying "no, Y, according to source Z" is a bit better, but it still leaves you with dueling sources and no reason why the reader should believe your source. A really strong reply is "no, Y, see source Z to explain what's wrong with the source the parent cited".
So... can you give us some reason why we should believe your position, instead of the GP's cited one?
Here's some sauces: https://www.clo.nl/en/indicators/en022909-sea-level-dutch-co...
https://research.csiro.au/slrwavescoast/sea-level/sea-level-...
https://www.stats.govt.nz/indicators/coastal-sea-level-rise/
I see people make this argument sometimes, but all it probably indicates is "mega-rich people can absorb a monetary loss", not "they don't believe it exists".