Hard to tell since most people in this forum will most likely use random name on gambling sites. Not even close for me, I am around 1000th with over 2k players participated and there are only 313 paid places
It's good for privacy because if you use same username on different platforms, your privacy and anonymity can be broken if it is known on one of many platforms.
How you use emails for account registrations on many platforms matters for your privacy and anonymity too.
Bitcoin privacy guide.Mail of a thing needs to be handled with care as it exposes someone the more, but for someone who can't controlled the used of several mails can actually used a particular mail but which can actually change username on the gambling site, this can also make someone hidden if they don't repeats their password used in other forum and gambling site. Then other important thing is to avoid using passwords or pin or even enable marketing mails, sometimes it affects you and if you can't control a particular mail then it's important to use different mail which you have access to.
For privacy reasons it is good for a gambler to change usernames with few emails. But if the gambler changes email address as the way he is changing usernames, it might affect him later either in the time of updating the KYC or documentation so email address should be sensitively handle. Many people don't know this so they use one username for all the casinos they are registering which will definitely complied to reveal your identity one day in the Internet. Though people are using one username for all for easy access.