Obligatory reminder that the Dropbox thread ends with "I only hope that I was able to give you a sneak preview of some of the potential criticisms you may receive. Best of luck to you!" The comment didn't dunk on Dropbox as an idea, but pointed out that they would need to highlight their moat wrt copycat competitors in order to convince sceptical investors.

The artist in question is presumably not raising VC money, so concerns about long-term viability of the niche if other artists start imitating the style probably don't apply. (Maybe it's even the reverse situation, where increased production of cracked-glass art raises the profile of the trailblazer and increases the demand for "originals.")