I don't know how it is in France, where you are ... but here in the U.S., it takes years for makeup artists to get to the point that they are doing makeup in magazines an in fashion shows ... at least as the key makeup artist. All of them dream of this world, but almost none of them ever get to do that kind of work. And it is not how you make your money ... acutally ... it pays very poorly.
Most makeup artist start their careers in Sephora, behind a department store counter selling makeup or doing weddings, because it's impossible to make a living doing magazines and shows and nothing else. These glamor jobs are just to build your portfolio and resume ... you make you money doing things like catalogs and advertisements ... which is not creative at all. You must just produce what the client wants. If you get lucky, and make the right connections, you could get hired for TV or films ... but that is not as creative as you think, unless you go into special effects makeup (which is another career, altogether).
Then, it's extremely competitive to get the "glamour" jobs you probably want ( the ones that don't pay you much) ... and you have to have a solid foundation of the best portfolio, a good reputation and lots and lots of connections in the fashion world to even get noticed. What you want to do is not a realistic outcome ... it's once chance in thousand and you must do a lot of other types of jobs to support yourself.
Therefore, ... your parents are right. You need to have some backup plans and the more you know, the better chance you will be able to support yourself in the beauty industry.
You can always do the creative stuff by testing with photographers and sometimes that can work into opportunities. That is done on your own time, using your makeup (which is at your own cost) but it's the fun part of working in this business. And you always will need to test to keep your portfolio updated.
There are a few threads here about all of this:
- Becoming a Makeup Artist - training, schools and breaking into the biz,
- About Your Portfolio and Testing, for Freelance Stylists, Hair/Makeup Artists etc.(needed if you want to work in fashion as a freelance makeup artist)
- Freelancers (Stylists, Makeup Artists, Photographers, etc.) - Marketing Yourself (it's your own business and you must find work every day ... this is how we do it).
- Creative Agencies ... Representation for Stylists, Photographers, Makeup Artists, Etc (sometimes, if you get good enough, you can get an agent and they will send you out on jobs),
I suggest that you read these ... they will give you a bit of insight as to how it will work and what to expect if you decide to become a freelance makeup artist.
My suggestion ... take the more extensive course and you will have something to fall back upon, if you don't get anywhere in your freelance career. Remember ... most fail, and those that make it ... do more mundane work most of the time. Only the top 1% (or probably les) actually find fame and fortune and get to be creative all the time. Maybe you can make it ... but it won't be easy and you will need to support yourself in the meantime.