Gamble for fun, don't get obsession with it, that is the simplest thumb rule should be followed by everyone.
Responsibility is to some extent equal to professionalism, since a professional will never take risks beyond measure or play with other people's money without warning those whose money it is about possible risks. Another question is that we know for sure that responsible players exist, but are there professional players who profit from gambling? From the point of view of mathematics, they should not exist, and those players who play a lot and are still in the black are either a fluctuation or earn not on gambling, but on something related.