If you are going to invest for long-term, either Bitcoin or Altcoins, you have to make sure that the project has a solid plan on their roadmap and have a good community. Having a good community gives you an idea that the project is a good one. Yes, it is reasonable to invest long term in Altcoins because it gives you a passive income that you can harvest in the future.
But, always do your own research as crypto world is very risky and we know there are a lot of projects out there that are just a rug and pull token.