Its about the competition. Those developers have seen the potential of bitcoin and they are applying what happened to it and looking forward for a better result.
Aren't you curious that each of them calling themselves that can replace bitcoin in the future and better than it. They keep on creating coins with that mindset and each of them think that this is the chance for the emerging tech to take over and their creations will be the one that will be on top.
which will not be possible No matter hard they tried because they are all imitation. they kept on copying each other in terms of strategy, business plans and ideology. the first 20 coins in the crypto ecosystem has shown there uniqueness and there different ideology and that's why there are ahead. the little problem facing those project at the top is the idea behind the forking. this will give hope to uprising projects.