It's the total of all credits from your members but it's of no current relevance:
1) It shows the amount of credits they earned in tournaments and by tiering up,
2) it disregards further income by Brackets and Match Challenges,
3) it disregards what they have spent.
Thus, it's just a bragging number.
Furthermore, it's shown here correctly as credits but displayed falsely as $ elsewhere, in the CC lists, in tournament leaderboards, on the players' profiles and on the top earners' list on wgt.com.
This is false because the T&Cs state: "Credits have no monetary value."
So guess why they show the phantasy amount of 61,000 "$ career earnings" on their front page?
WGT has avoided or declined more than once to explain how credits are converted into $ at all AND at the alleged rate. Homi soit qui mal y pense ;)