I would say that a 'pro' meet two factors:
You spend more time playing poker than you do any other money-making activity.
Your poker winnings are sufficient to provide for your essential expenses.
So winning one big tournament does not make you a professional. In addition, someone who is a high-level hobbyist who plays 30-40 hours a month (or a half-dozen tournaments per year) is also not a professional, even if they have made six figures over each of the last few years.
On the other hand, after you have become a 'pro', then the definition changes - you can remain a pro even if you end up making more cash from endorsements, appearances, consulting, then you actually do playing.
Currently, personally, I am on the road and strive for this
))
Alex.