When Dropbox launched, there were at least half a dozen other “online storage” businesses in existence. The Apple iPod entered a market litered with crappy MP3 players. Google was famously the Nth Internet search engine. Stripe launched into a market crowded with Braintree and Paypal, and before that Authorize.net and others. Uber was not the first way you could order a taxi, although their spin on black cars was unique. Facebook was yet another social network in a market “saturated” by Myspace, Friendster, Orkut, Bebo, Hi5 and others.
Some good ideas have a lot of bad implementations before someone comes in and does it well enough to win big.
Some words of wisdom for entrepreneurs that too many people forget.