Do I really need to write full time to be a successful writer?

I think no. Success in any field does not depends on time. To be a successful writer, one should be well equiped with correct information, and khowledge on the topic, skill of writing appropriate sentences, and most of all honesty with his profession.

The most important is the culture of the individual and consciousness towards the issues of the community; story writer I am already, and rely in some nonfiction on documentary information and sometimes the other side of televised reading

not necessary

A little bit yes and no. you should focus on writing till you build a passion towards it. After that you can let your self wander.