Buying a yacht
This comment by Jeff really struck me:
I strongly believe that weight, in and of itself, has no inherent virtue and is by its very nature a very serious liability.
Back when I used to have time to subscribe to and read Car and Driver, they had a sharp columnist named Setright who could be counted on for informed and interesting takes on automotive issues and conventional wisdom (he once argued that the received wisdom "racing improves the breed", which came from horse racing, was basically a myth when applied to automobiles). Setright did a column once on this very theme, i.e. that lightness was a virtue in vehicles that was its own reward. I think I''d have to agree with Jeff; the only time sheer weight is clearly an advantage in a vessel is when you want to use it to anchor an artificial reef.