there are some singers who can sound beautiful without training eg Billy Holiday.
Also some singers would probably lose the 'character' of their voice if they did have vocal training eg Nick Cave, Bob Dylan, loads of pop and rock singers.
The best singers are ones that practise loads though, even if they don't have formal training. It's like anything else innit. And the earlier you start the better.
From your post I assume that you can sing in tune? It's very very difficult to get an adult to sing in tune if they can't, tends to be something learned in childhood.
If you can't sing in tune, I would give it a miss tbh, unless you're prepared to put in an awesome amount of effort.