My worst (and by far the largest) investment is federal income taxes paid. Learned nothing since I don't have a choice.
Paying my income tax is a GREAT investment. I do not go to jail and the IRS does not do bad things to me. Money well spent.
My actual bad purchases were pre-boglehead days. My overall portfolio did better than the market (because I lucked into one stock that almost tripled and it was 1/2 my portfolio). I realized it was luck because of the other picks that I had (which were not good).
Two of the stocks were:
BioSolar (a company in which I still have stock), which had a reverse split. I had something like 2000 shares, and now I have 40. I am still confused about that one. Why do I still own it? I am afraid that I will owe money in commissions if I sell it... the value is close to the commission to sell cost. This was a feel-good buy that I thought would do well, as it was trying to find a way to create non-oil based solar panels (using renewable plant materials!) I thought it would also be quite profitable. Unfortunately, it did not invent something good enough to be purchased, it would seem.
BioStar Pharmaceuticals: A Chinese company that was producing hepatitis medicine for rural Chinese. (Another feel-good one.) It looked like it had a solid growth potential. It was a long-term buy. Unfortunately, there was POISON in the capsules used for the medicine.
I still own this one because it recovered well and is back on the right track. I think that it has potential from where it is. I am unsure as to whether I will need to harvest it for tax losses now or in the near future, but I will do so. If I do not have as much loss to harvest, well, that is not a bad thing.
Overall, I made more money on the crazy portfolio than if I was invested in index funds. I realize that this is due to luck only (One stock beat the market by a lot; others did not beat the market, and the above two tanked. I made money (I prefer to view it as an overall strategy that worked by accident than many losses and one good gain), and I learned an important lesson. Don't rely on luck. Also, the gambling rule is to stop while you are ahead. I am ahead, so I stopped gambling and became a boglehead.
Thankfully, the overall
I'm not a financial professional. Post is info only & not legal advice. No attorney-client relationship exists with reader. Scrutinize my ideas as if you spoke with a guy at a bar. I may be wrong.