Hey guys. Just to clear up a little misunderstanding I've got. There's something I don't quite understand and it is what happens after people hodl coins and altcoins.

So, we all say that hodling is better than trading, yeah? And I think the only way to earn from cryptocurrency is by exchanging it for fiat currency, right? Meaning, the hodling is just for the value to increase over a while and then you still trade it right?
And for the altcoins, after buying altcoins, what happens if no one wants to buy them from you? You know a lot of altcoins aren't all that popular so how do people even sell off their altcoins? Can you even hodl altcoins?

I know those are a lot of questions, but I keep on getting it wrong in my head. So thanks in advance for the answers.