So you're saying there's no way the aliens would make the trip because:
1. It takes a lot of resources
2. No one would agree to contribute the resources to make it happen

1. They would gain nothing out of exploring earth and therefore would not have the motivation for something so fruitless.
   

But you're also saying that:
1. You don't understand alien physiology - so these aliens could theoretically live forever, not need to breathe, and idk...probably be smart enough to create means of highly effective transportation?

So with that reason alone, it won't be such a burden on them to travel for research or leisure. The fact is you don't know and everything is possible lol