Jacks of all trades, masters of none.
Amazon is the same. They offer so many products and services that there are literally thousands of things they miss, gaps to fill in, opportunities to capitalize on.
There is no shortage of commerce to go around. It might seem like there is too much competition, but the truth is, there's not enough innovation. Sure, you might not be the first to the market, but that doesn't mean the market still doesn't need what you have to offer. Don't lie to yourself before you even get started.
There are literally 10 barbershops on my 5 minute walk to the Subway - and they all do well!
How many shoe companies can you think of off the top of your head? And there are new ones popping up every day.
Don't let the competition scare you away. No matter how many other people do what you want to do, you can still bring your unique flare and stake your claim in a small corner of the market.