Can we get robbed of gold in Skyrim?
Solution 1:
No, you cannot get robbed in Skyrim. If you are selling items maybe you have 10,000 and just misread. Or maybe you were accidentally buying items from the shop keeper instead of selling to them.
It's also possible it's a glitch, but I can assure you no one can steal from you in Skyrim.
Solution 2:
I have totally bought like 10k worth of items, thinking to myself "I don't remember picking that up, but I sure want to get rid of it." Yay for quick-load. It's also why I always quick-save just before bartering - just in case I do something stupid.
I have noticed items disappearing from me early in the thieves guild quests though. I picked up the Thieves Guild armor upon entry into the guild, handed it to Jordis, then a bit later when I was transferring stuff to my various chests in Whiterun, 3/4 pieces of my Thieves Guild armor was gone (no idea what else may have been missing). I think I just did something dumb, but it is remotely possible there's a bug in that area.