What's the most expensive mistake you've made?

[EmeraldJackLegacy]

Most players eventually learn a lesson the hard way.
Whether it was chasing losses, ignoring bankroll limits, or trusting the wrong casino, I'm curious what mistake taught you the most.

 

[casinobonusguy]

Nothing to do with the industry but we loaned a family member $xxx ,xxx ,it was suppose to be a short term loan until they sold their home .Markets went tits up and then they went bankrupt on us .It is a tough lesson and has affected me greatly .Trying to sort it out but has not been easy .