1. A big loan or a huge amount of money
2. A lot of experience in running a business, that's for sure(if you're goal is to be as big, or bigger)
3. Good developers and overall personnel(customer support, lawyers, etc). This should be self explanatory
4. An excellent marketing strategy. If you want to have a slight chance of de-throning Coinbase as one of the best exchanges
5. Be bald (jk)
^ And that's just the very tip of the iceberg.
However, you can do an ICO if you don't have the require capital and easy your expenses you could also offer the team some percent of the token has their fee.
ICO lol? You think Coinbase is an erc20 token or something?