Babe, I'm constantly making mistakes. I'm not ashamed to say that. That's how most of us learn going through life, and I'm no different. And I don't consider most mistakes to be disasters, so I don't dwell on them. Since mistakes often serve as a jumping off point to learn something better, it's difficult for me to look back and say, "That was my biggest mistake."
We did make a mistake in the beginning of our Hawaii move that cost us $10,000, so I guess you might call that our biggest mistake. We bought our first piece of land a few years before we planned to move. But a combination of our ignorance about how things work here and the incompetent county building department here, we were led to believe that we would not be allowed to build on that land without an expensive and lengthy battle. So we sold the land and purchased our current place that became our homestead. We took a $10,000 loss. Ouch. Double ouch.
Other mistakes involve buying the wrong equipment for the job at hand, going the legal route with the house building project of getting a building permit (that cost us thousands and made us suddenly visible to the authorities) , and shipping a bi-metal horse trailer over here (the vog and constant moisture destroyed it).
I don't consider any of these mistakes to be disasters, though some were costly and some vexing.
All the time I make little mistakes....
...growing the wrong veggie varieties for my area
...planting the wrong fruit tree for my elevation
...trying to plant the wrong things in the boggy area
...deciding to buy the cheaper quality fencing
...going with goats when my fencing wasn't high enough
...buying the wrong woodstove
...laying cinder in the driveway instead of gravel
...buying pressboard or composite furniture in my wet climate
...putting doors on the kitchen cabinets and bedroom clothes closets
But to offset those mistakes, we've made plenty of good decisions. I suspect many of them were the result of dumb luck. .....
...bought a full sized 4x4 pickup truck with a towing package
...opted to build the house out of treated wood and finish it with cedar
...put in extra water catchment tanks
...installed an off-grid solar electric system
...installed a small woodstove in the livingroom
...enclosed the lanai (porches) to expand the living space
...made a rockwall across the front of the property
...decided to raise livestock
...decided to go non-traditional for storage, that is, open shelving and no cabinets or closets, even in the kitchen.