What do you need? Food and shelter? Friends? Relationships? And what makes these needs as opposed to just wants?
The first and most obvious difference is consequence. When you can't find shelter, that's a lot bigger problem than when you can't find a decent cafe. If you run out of ice cream, you might be sad, but you won't starve. Measured that way, needs are just the wants with the highest stakes. But that doesn't tell you how much consequence you need for a need.
And as soon as you get beyond purely physical needs, consequence becomes tricky to define. Eating is high-consequence, sure, but what about a relationship? You might be deeply unhappy without it, sure, but you won't die. And if you set deep unhappiness as the bar, then getting to see your favourite football team is a need too. We'd be unhappy to miss out on anything we want, but that just puts us back at the question of, well, how unhappy is unhappy enough?
I think a better way to look at it is to work backwards from behaviour. How do you act when you want something vs when you need it? If you want to eat, you might check the fridge, realise there's no food, find that the restaurants are closed, and then give up. But if you need to eat something, you don't stop there. You go to the supermarket. You check if the neighbours have food. You go door to door. You beg on the street. Needs don't permit giving up.
It's easy to give up on wants because often you just want to feel like you tried. Well, couldn't find a good cafe, but I had a look around. Couldn't buy ice cream, but I checked the shop. This is the minimum effort required to show that you did something that could feasibly have resulted in your goal. Who's going to criticise you when, clearly, you put some work in? But you can't say, look, stomach, I tried to find food so don't get hungry at me. A need doesn't care about effort, only results.
So I think there are more things that we can recognise as needs. Food and shelter, sure, you're always going to do everything you can to get them. But what about things where the consequence isn't starvation, but a slowly growing sense of dissatisfaction? What about the things you need, not so that you stay alive, but so that being alive is meaningful?
Letting your dreams be wants rather than needs – saying that you want to make music or write novels or raise chimps in Zimbabwe – is to say that you'd be okay if you gave them a shot and they didn't work out. But are you really okay with that? Would you be satisfied, looking back on your life, knowing that, well, it was worth a try?
If not, then what you have there is really a need. And it's worth thinking, what would you do for that need? Quit your job? Ask people for help? Move countries? Leave a relationship? If you'd do those things for food and shelter, why not do them for a dream?