What are the biggest mistakes you've done with Bitcoin?

[Matthew N. Wright]

Cashed out all my casascius coins (50 BTC worth) at $27 to pay some debts.

[WikileaksDude]

Cashed out all my casascius coins (50 BTC worth) at $27 to pay some debts.

some debts..

sent 45BTC to an anonymous mixer on TOR.. they never returned

[mpfrank]

Accidentally received coins from a friend to a bit-bill in my (physical, leather, back-pocket) wallet whose private key I had previously posted on my blog as an example.  The coins got swept after only 1 or 2 confirmations.  Fortunately it was only lunch money (although someday it might be worth a few solar systems).

[Matthew N. Wright]

Cashed out all my casascius coins (50 BTC worth) at $27 to pay some debts.

some debts..

sent 45BTC to an anonymous mixer on TOR.. they never returned

Ouch. Was it a well known one?

[goxed]

Lost 7,4 BTC to a thief. I was stupid enough to keep a hot wallet in a windows machine.

[Turbo1980]

Discover Bitcoin Two years later 

[keystroke]

Lost 7,4 BTC to a thief. I was stupid enough to keep a hot wallet in a windows machine.

How exactly was the machine hacked?

[goxed]

Lost 7,4 BTC to a thief. I was stupid enough to keep a hot wallet in a windows machine.

How exactly was the machine hacked?

I am still unable to figure it out. I have installed an antivirus (avast) but it found no trojans yet. The BTC was stolen yesterday, I think the wallet might have been purloined sometime last month.

[Transisto]

Purchasing a BFL with bitcoin early.  If I make back 30% of what I paid for it I'll be happy.

[BTCisthefuture]

1) leaving some btc in instawallet.  no word yet from them on how serious their security breach was and if our coins are safe.  that might end up being a mistake for me, hopefully not though.

2) thinking i knew how to day trade. luckily i only lost a very small amount but the constant small loses made me realize i dont know enough to be playing that game

3) thinking bitcoin was really awesome 3 years ago but never jumping on board until recently. that one really hurts.

[notig]

I bought a butter fly labs single for 1333 instead of buying 1333 worth of bitcoin  (at the time btc price = $15)

[keystroke]

Lost 7,4 BTC to a thief. I was stupid enough to keep a hot wallet in a windows machine.

How exactly was the machine hacked?

I am still unable to figure it out. I have installed an antivirus (avast) but it found no trojans yet. The BTC was stolen yesterday, I think the wallet might have been purloined sometime last month.

Why do you think it was stolen last month? Was it an encrypted wallet?

[tvbcof]

Lost 25 BTC by sending to what I thought was my instawallet... But it wasn't. Instawallet is just a bit richer because of my stupidity.

Lost 20 BTC by sending to what I always considered to be ~davout's wallet...like every instawallet.  Hoped he and his had the skill to keep them from getting stolen (what with his mainstream bank operation and all) and the integrity to not steal them himself.  But hope is well known to be a lousy strategy.  I hope now that he can get them back on-line and under my control.  If not, I never relinquish control of more BTC than I can afford to lose and chuckle about a bit in the process.

The 50-ish BTC I sent to my instawallet as pocket change were worth about $150 worth when I put them there, and it has been quite convenient over the 1.5 years.  The 40-ish remaining suddenly became worth more than I wanted to chuckle about losing so I sent half to Mt. Gox a few days ago.  Lucky timing.

Instawallet made it a point to advertise as being for spending money and had only modest security.  That was front and center on page...or at least it was at one time.  I've go no complaints about losing it, but ~davout and crew need to accept their black-eye like men if they end up losing these funds.  He is not shy about calling others out for being clowns.  OTOH, I've not seen much from him lately so he is probably either really busy...or retired comfortably in the Bahamas.

[wopwop]

Played satoshidice

[boscorocks]

Lost 7,4 BTC to a thief. I was stupid enough to keep a hot wallet in a windows machine.

How exactly was the machine hacked?

I am still unable to figure it out. I have installed an antivirus (avast) but it found no trojans yet. The BTC was stolen yesterday, I think the wallet might have been purloined sometime last month.

Your mistake and mine the same. I didn't find your transaction on the address mine went to (thought it might be related). There are two other people who had 9+ BTC go there. I was being lazy/distracted about putting my BTC on an offline computer BIG MISTAKE - take heed all ye noobs!

[Parazyd]

Selling at $30 and not mining when Bitcoin was just introduced.

[mb300sd]

lost a 5k+ btc wallet to a hard drive way back when
bitcoinica
pirate
bad trades
satoshidice
cashing out 5% at 32
...
the list goes on, but I'm still in an ok place, and far better off than I would be if I never got in.

[Transisto]

BITCOINICA

[b¡tco¡n]

Spending BTC100,000 on a few pizza's. It's not the $14M I would now have that bothers me. It's just that I can't lose the extra fat and love handles I now have. 

[carborundum]

1) Not mining harder two years ago, I bought 1x5770 when I had space fro 3x ( I didn't realise I sould use PCIe 1x with a riser)
2) Not discovering Bitcoin 6 months earlier
3) Not mining in winter of 2012

Could have been rich.... now I've only got pocket money