Over the last 15 years, I've made every investing mistake there is to make. Some twice. A few of them have been deeply painful. At the time, I never imagined I'd say this, but I'm grateful to have made them.

I've lost money investing in bad businesses I thought were undervalued. A heavily indebted microcap reliant on a single product line. A struggling retailer. A black box financial I thought I understood. Thank god I lost money on these things because I deserved to.

I imagine an alternative outcome where I actually made money on these. What a curse that would have been. I might still be sifting through dog shit today thinking that was the road to long-term wealth creation. Or more likely, I'd be in a different line of work.

That's why I don't think we truly learn from reading about the mistakes of others. At least I didn't. I had read all the letters, books, studied the greats. It wasn't until I felt that pain, that tormenting anguish, that regret from real loss that I completely internalized it.

Losing money is terrible, but in my case, the losses were painful enough to cause big improvements to my process. Counterintuitively, my investors and I will be much, much, much better off for it in the long run.

It's painful to rehash this, but hopefully there's a lesson. Get into the arena with real money. Make your mistakes and rub your nose in them. Figure out what actually works over the long term. Patterns begin to emerge when you do it long enough.