in the midst of Hong Kong's materialistic culture, its unsurprising to find creative energies being suppressed...or worse still, harnessed in marketing which serves only to prop up its increasingly material and spiritually empty culture.
A formal training is not a requisite for being a successful artist - witness the masses of talentless artist-wannabes whose exposure lies within the marketing paradigm, or worse, the social butterfly phenomenon.
Your path seems to straddle both paths: firstly, the development of painting technique and its methods, which later, must mature into artistic vision. Without the technical background, any endeavour would result in apeing crudely, with weak insight into contemporary painting.
The second aspect of converting an interest, a passion or a hobby into an earning profession, will have less credibility without a formal training. Many still rely on who they know, or their networking with family and or friends to promote their work to a sustainable career level.
If you are more inclined towards a love for the creativity and process of becoming an artist, I'd recommend trying an evening painting course. You can supplement this by going to the Wanchai Exhibition Centre to find info on courses, and attend exhibitions in Hong Kong, in order to fathom whether disillusionment is likely, or whether passion will endure. If that wets your appetite, many evening part time courses exist in Kowloon and Hong Kong's colleges. Most are rapidly filled with middle-aged crisis lookalikes, others are in Cantonese which may exclude some. If you haven't given up after a year and switched to learning the piano or bungee jumping, then maybe taking a full time course would be a good compromise between earning and starving. With painting, its not quite the same as photography where every digital toting camera owner thinks he is a photographer (and unfortunately it is mostly always a 'he').
There is no reason to starve as an artist, unless one pursues artistic integrity with financial and complete recklessness. Such Victorian nostalgia does however lend itself to a fantasy that an artist is giving up more (of the material) in order to pursue his art. This itself is no better than an inverse superiority complex.
In any case, studying a general fine arts degree or studying with a group to further your learning would be much better than posting for 2 cents (or more) on the internet.
Best of luck on your journey.