Yes, some altcoins are just designed to fail and because of that there is no possible utility in them. But still I won't say that all altcoins are worthless that isn't right. Bitcoin stand's top over all other coins because of the utility it offer  us ,but still don't forget that there are other altcoin projects like Ethereum, which was not created to be another currency but as a decentralized computer .
When you research deeper ,you will find out that those altcoins that fail are most likely to be aspirations for certain projects that are supposed to be better than Bitcoin but most of them end up becoming scams or failures. The main issue is that some people do not understand the difference between a project that has innovation, purpose and a token without any value. What people should prioritize is to learn the key difference between both. Furthermore Bitcoin is the safest and most important cryptocurrency, but for altcoins not all are safe, many are failures still There are few that has real purpose and value.