Survivorship bias?

I'm aware that by surviving as a business for 41 years I tend to look back with a survivor bias. I succeeded because I did this or that, instead of maybe just being lucky. Or simply by surviving, I give too much credit to my own attributes. 

That said, I do think I managed to avoid that one big, killer mistake. Looking back, there were a lot of decisions that could have gone either way. 

I made a ton of mistakes--some of them were very close calls. I remember walking to the corner near my store every day for years thinking, "If anything happens today, we're done."

I did start to pile up experience after awhile, and much of that experience came from trial and error; learning as much or more from the errors as from the successes.

Eventually, I felt like I could look at other business and judge their viability by the decisions I saw them making. Of course, I couldn't see the hidden attributes--their level of perseverance or how many resources they had in reserve, but generally speaking I could see if they were zigging when the market was zigging or zagging when the market was zagging.

When they zigged when it was zagging, I'd think, "ah, oh." 

So...Killer mistakes:

Over expanding. (My biggest mistake. I call it the Duncan Corollary (😀) to the Peter Principle. A business owner will expand to their level of incompetence.)

Not recognizing a bubble. (We're all forgiven our first one.)

Under-expanding or not having enough inventory. This seems to be fueled by the business school models of turnover and selling only the bestsellers, carrying what everyone else carries,  instead of making your store unique. Either that, or spending too much money on overhead and taking home too much money instead of buying product.

Too many employees. (Don't own a store is you don't want to work it.)

Letting a manager run the store before it is established. If you run a Mom and Pop business, you make enough money for Mom and Pop--or a Manager--but not both. At least, at first.

Moving uptown or downtown instead of improving existing location. (I suppose not moving when you have a bad location would be equally bad, but I never made that particular mistake.)

Losing zest for the business. (Keep looking for ways to renew your interest. I ain't just about the money.)

Overbooking and overworking. (Big one; I think as many businesses fail from burnout as from lack of money--and the two are inextricably linked.)

Trying to underprice everyone else instead of trying for a retail markup. Conversely, you don't want to overcharge either. Early on, someone told me that you need 40% gross profit margin, and that the closer you charge to retail price, the healthier you are. 41 years later, this still holds true. 

Spending too much money on looks or brand or on advertising. People put way too much stock in "image." It really comes down to whether you have what the customer wants at a price they're willing to pay. They may like your shiny fixtures, but it doesn't mean they'll pay more for them.

Having lousy customer relations. (The number of stores who don't greet their customers is amazing to me.)

Not seeing when a product is dying, or guessing a product is dying too soon. 

Not doing the math. Sometimes there just isn't enough longterm demand, no matter how hard you work or how winning your personality.

Not diversifying. This is a big mistake in Bend. Specialty stores will do well at first, but if they falter or their specialty falters or they get increased competition, they have nothing else to fall back on. Up until recently Bend wasn't big enough to do that. And even if it works now, why not have some backup?

I'm sure there are many more, but these are the ones off the top of my head.