I made one mistake with SFI. I bought some Tcredits and tried to win some more in auctions. This in itself is not a bad thing to do. However I did not read the rules. SFI gives us rules for a reason. Now I am trying to win it back by making 3 free entries into the Daily Grand. I won't consider quitting SFI because there is no membership fee.
Note: Tcredits are very easy to spend because our mind may not perceive it as cash.