Life is too short to learn any language, even English and your mother tongue. Think about it. Do you really know all the words in these two languages?
Not even a British could recognise all the vocabularies in the Cambridge dictionary. And you can't write the original characters for all tricky cantonese expressions.
But if you just want to talk to a native speaker, you don't need to take a life time to master it. Just intermediate level which takes you a year to reach is fair enough.