It was on a buy order, I am guessing you selected the price field which already included the default “highest buy order price” and accidentally forgot to clear it before entering your own price and doubled the digits in the price.
It happens and then usually a warning window comes up to say something like “are you sure you want to set your price at 90,834,589,023,748,237,421% above market average?” but of course you get so used to clicking through things like this you do enough trading it is going to happen eventually.
It doesn’t help that the networth estimation is so out of sync in this game that it is common to see the warning come up with hundred of thousands of percentages above market average value.
Myself, lost billions multiple times. Maybe even as much or close to your 30 bil loss overtime but not all at once.
What I learned is you don’t keep all your isk in the same wallet for multiple reasons. Have a wallet for buy orders, for different divided sections of buy orders, different wallet for sales income. Don’t keep more isk than you need to pay all your buy orders if filled. Don’t use your profits wallet to make general purchases, make them with the clones wallet and only transfer as much isk as you need to pay what you know you need so if you make a mistake you don’t have the extra isk to complete the actions.
Another thing that can happen is you set your sale price on the market too high and end up losing billions to broker fees again setting your price trillions of percentages higher than average and again skip clicking through the warning like it was nothing because of complacency.
Fortunately on losing isk to broker fees you can file a ticket to get your isk back, still never bothered to do that myself it was just a few billion over a period of months. Unfortunately any mistake where your isk goes to another player cannot be recalled by CCP and refunded.
Sorry for your loss, someone else is having a time I bet but no you definitely don’t get the record for biggest dumbest mistakes in this game.
Eve is about loss, the longer you play the more your loss. What keeps players with the game is accepting and taking those losses, learning from them and pushing on.
It gets easier with time but it is ok to feel like shutting the game off, uninstalling it for awhile and going somewhere else to do something else for awhile. Your not going to feel like playing too much at this moment you need to get through this bitter stage like anyone of having just had such a loss first and then eventually come back to push on when it doesn’t sting as much.