Yes when one approach gambling like they can not do without it, it would be obviously clear that they are addicted. I will agree with your opinion that not only people who lose games are addicted, both constant and regular winner's to could be addicted because they too play everyday and luck always is on their side so they win game's too regular. Nobody would say much about them because they win but those who constantly lose are the talk of the day as there is no impact they have made and that would result to them being called all sorts of names.
True, when issues of gambling addiction arise, minds are always drawn to the loser because losses are visible and undesirable outcomes. Even this causes people to criticize gambling because losses are always viewed as products or gambling, providing a foundation for criticism.
However, winners are always recognized. A person who encourages someone to stop gambling simply because they are losing may be tempted to gamble again if another gambler wins. Winning covers addiction and that is why a gambler who is winning is never pictured as an addict.