I seriously doubt there are anywhere close to a million or so actual players here. Those six or seven million accounts include every one of those that have become inactive since WGT started over 6 years ago. Randomly browsing the WGT members list shows a lot of accounts started between 2007 and 2009 that have not shown any activity since.
WGT has never purged their inactive accounts. It allows them to engage in false claims to advertisers and prospective members.
Many people like myself are concerned about providing too much information for personal security reasons.