What is the stupidest financial mistake you’ve made?

Same. Finally got my first house in late 2006. Could have gone another £40k on the mortgage offered but went cautious and bought a cheaper one that needed some work. Spent about £10k getting it fixed up. 18 months later the arse dropped out of the market and with the extra we'd spent on it we were basically borderline negative equity. But could have been £50k in the hole if we'd overstretched. But we had no reason to move so waited it out, got better paying jobs, waited some more and paid off over half the mortgage. Meanwhile the house value had nearly doubled. We'd outgrown the little starter home, 2 kids and starting to feel cramped. Had the choice to stick it out again, be super cramped with 2 teenagers and 1 bathroom but be mortgage free or cash it in and make the big move to the forever home but take on a bigger mortgage Despite being between Covid lock downs sold at a decent price, bought new place at a spectacularly good price (neighbours across the road bought exactly same model but with half the garden size, on the same street for £50k more 3 months after us) In the 3 years since we've done a little work which has added value, presciently had locked in the fixed rate for 5 years, and conservatively it's worth £100k more than we paid. Similar houses on the block have recently sold for £150k more than we paid. Academic as we don't plan to move for 20 years or so. But we're probably sat with about 50% equity and will be not happy but OK for mortgage payments when we're out of fixed terms,with a loan to value that should make it easier. After a lifetime of zigging when the market zagged, being forced by circumstances to tick whilst everything else tocked finally finally managed to get on the right side of the macro economics. Took 20 years to course correct all manner of disastrous resets; sudden death of parent, multiple redundancies, car engines blowing up, motorbikes being stolen, pretty much a laundry list of every poor financial decision or bad luck that could happen. Made the biggest gamble of my life right as the world was self destructing and ended up being the best decision ever. If we were looking to buy now, we'd be looking at something smaller than our old place, in a worse area. And that's assuming I could even get a mortgage with the way the banks are pulling back offers (I'm self employed). If we were looking to rent in this area to keep the kids in the same schools we'd be paying around 50% more than our current mortgage, if we could even find somewhere. In hindsight it was a huge gamble but it has paid off and I'm hugely aware of how lucky I am when I look around and see the mess other people I know are in right now.