Topic 5567305
It can very from person to person but their number might start to make more sense if they actually reach that level of bankruptcy and then makes the statement.

Of course we suggest the safer side as 10% but there might be people who can sustain much bigger percentages. I am yet to see them have any stable financials though.

Just make sure you follow them and see if they are actually spending that much along with how much time they spent. That will decide on addiction being there or not.
For each person this level will be different, some people may be able to lose 10%, while for others even 1 or 2 % will already be too large an amount if they lose it every month. That is why this rule should not be generalized for all players. You need to assess your own capabilities without paying attention to how other players do it. And probably a clear sign of addiction will be that you start increasing your gaming deposit. If for a long time it was the usual few percent and you systematically increase it, then this is a sign that you should pay attention to it.