Not getting seriously involved with Bitcoin when I first came across it late in 2011, I though it was an interesting thing but did not try to learn more about it or invest in it.
I would have loved to have heard of it in 2011 i got involved as soon as i heard about it. That is a very big mistake by you, was the difference of you possibly being a mega whale millionaire and now having less than 100btc. It is easy to say in hindsight but must suck.
My worst mistake with regards to bitcoins is that I used blockchain before and my wallet got hacked due to a virus. From then, I am only using offline wallets and on a pc which is not connected to the internet. I also advise others to not use online wallets.
That was a mistake many of us made luckily i never leave of have left enough to be a problem. Was the mistake not using 2FA?