First of all, I must say the 2 replies to this thread,just before mine were amazing and I really expect this thread to turn out to be very interesting !
I mostly play poker, and I have had many sessions when I had been sitting in front of my PC for hours without getting ANY decent hand to get in the pot. It was so frustrating and made me feel I had thrown some of my precious free time down the drain.
Whenever I decide to play blackjack, I also have some sessions when I can't seem to get a single $ from the dealer. Especially when I have something like J-8 and the dealer's first card is 10, and then he gets 3-3-3, I feel like breaking my monitor!!!
So, I suppose my precious free time and my patience is the two most valuable things I 've lost while gambling....