What about 6 months later when competitors arrive?
Not all markets are winner takes all or even close to it
Not all markets are winner takes all or even close to it
The competition (or sometimes faux-competition) lasts until investors get bored, then the unsustainable startups slowly go away (often extracting more money from the public on their way out, by means of an IPO), leaving a broken market that needs to be rebuilt, if it's possible at all.