Silicon Valley (the show) pretty much nailed this on a regular basis when shoddy-investor-guy warns against making money because you'll be worth less money because people know how much money you can make.
It's totally reasonable to eat a market while it exists, and then find a new market later -- or even decide that the shrinking market is actually ok, and you're content with your share of that market.
Unless you're the VC -- because you have a VERY high risk fund (almost by definition) and you'd like only 10-30% success but with 100x profits on those 30%.
This leads lots of tech companies to flame out, overstress, and build things people don't need, because the sane, logical ideas are the ones that are harder to find investment for (if they can't bootstrap them).
It's a weird space.