Therefore you have high chances to be accepted in a gambling signature campaign if you are a gambler with experience.
I don't think so. Most signatures campaigns don't state that only for a real gambler to be eligible as a participant. What you need is you have a good understanding or knowledge related to gambling, then you can be active to discuss gambling discussion. As long as the rules are still the same, being a real gambler doesn't improve your chance to be selected. But yes, being a real gambler makes you easier to understand various topics related to gambling since you experienced it yourself.