It is not half, it is more than half although we might not have the actual numbers gamblers that do this but they thing is that, gamblers that does this are much and thats called ignorance or negligence that cause them some shit later, what is important to most gamblers if they visit a gambling site to gamble is, to know if the gambling platform has the type of games they like to play, the minimum deposit and how reliable their withdrawal system is, infact they may not even care about withdrawals and proceed to play their games after all they will want to win first before they can think of withrdawing, as a result of ignorance, they neglect what they are suppose to have known earlier.
I will say most of the gamblers never bother even reading the KYC terms. Trust me, most likely no one read the full terms & conditions and policy as well. You can say this is the biggest advantage for the gambling sites. On the other hand, gambling sites just copy and paste each other just by changing some points and words. But the reality is every gambler should read their terms before registering on the platform, at least about KYC, withdrawal, deposit and wager conditions.
If gamblers did minimal research before they started gambling, I think they would get some basic idea about that platform. Especially on the forum, anyone searching may get some legit feedback. Trusting other social media is quite complicated since it could be manipulated easily. But the forum manipulation would be easily detected; at least gamblers should read the announcement thread of a gambling platform before they start playing.