When the new coin offerings came to the front, people thought its impossible to attain the same level of popularity similar to bitcoin because of many things. A few are
1. Bitcoin longevity has been a major attraction to people. The crypto-currency market place has been flooded by many scams, Ponzi schemes and all sort of bad vices which has resulted in total loss of investments for a lot people. But everyone notices the superior technology behind the bitcoin and that very faith has lead to its current place as the forerunner of cryptocurrencies as well as an exchange medium for all other crypto offerings.
2. Bitcoin has grown over the period to be the most valuable (price) among all other coin offerings in the cryptocurrency market sphere .
It would take a lot for other coin offerings to overtake Bitcoin but its not impossible. There are some other serious players with high intrinsic value such as ethereum, ripple, litecoin, neo etc.