Aren't there some areas where this is more true than others? There are dozens of good ideas in online selling/auctions/etc. that have failed mostly because they weren't able to overcome the entrenched incumbent, eBay, but may quite possibly have done well if eBay didn't exist. A similar hurdle faces anyone trying to take on PayPal, or at this point, Twitter (e.g. StatusNet's #1 barrier to acceptance is Twitter's dominance). I would imagine the Gmail juggernaut totally changes the playing field for anyone who was once contemplating a freemium webmail startup as well.<p>It seems that's a big part of the indifference equation also. If you say "I'm doing X", and everyone replies with "well doesn't [Big Player] already do X?", you have an extra hurdle to get over there: not just convince them it's a cool idea, but convince them you do it better or differently enough than the competition.<p>Though if he means only the more narrow: don't worry about competitors who <i>haven't actually succeeded</i> (yet), then I agree.