ConJosé, the 2012 Worldcon, had an operating surplus. On a gross of around $961,000 (including the Art Show gross, nearly all of which went back out to the various artists), the convention had sufficient surplus to refund over $100,000 of memberships of program participants, volunteers, staff, and committee, and also enough after that to pass along $30,000 split between the next three Worldcon committees. So do not let anything I say here lead you to think that the convention lost money.
But bidding for and chairing a Worldcon can be an expensive hobby. While I didn't keep completely extensive records (except for the couple of years where there were enough to justify itemizing deductions, wherein I got a few hundred dollars of tax relief because of it), but roughly speaking, I spent around $50,000 of my own money traveling around promoting the 2002 bid and then ConJosé after that. That's not expenses reimbursed by the bid and convention; that's money out of my pocket spent on travel (airfare, hotels, meals, etc.) to support my hobby of conrunning leading up to ConJosé.
I put myself in a pretty deep financial hole; so deep a hole that I simply couldn't get out of it and started digging deeper. A few years ago, I concluded that drastic action was needed, and I borrowed $50,000 from my 401(k) retirement account. As it happens, it looks like that might have been a pretty good investment, given performance of the market at times, since the loan repayment went back into my account; also, the 5% interest I was paying was a lot better than the >20% consumer-grade credit-card interest I paid off (and cancelled credit cards) with that loan. That doesn't kill all of my debt (besides my mortgage, I had other consumer-grade debt as well), but it was the most expensive and most-worrisome portion of it.
Two weeks ago, right after Westercon 66, I made the final payment on the $50,000 401(k) loan. From my point of view, my own personal expenses associated with the 2002 Worldcon were paid off as of July 12, 2013. Whew!