Quality seems completely lost as a goal in any shop. See Demming and Peopleware.
In very general terms: "founder mode" is more often than not toxic because it is taken out of context and used to scapegoat being an asshole. Much like the Steve Jobs worshipping of yesteryear.
Lack of financial oversight by board/investors including founders putting up company money for personal investments including moving money into personal accounts to try and inflate their credit ratings.
Non-VC startup: lack of preparing for a future where income is reduced for a period of time and keeping some amount of business savings around
VC startup: lack of appropriate fund handling given the assumption that the money machine will always be there
Hurting all option holders by removing the ability to exercise early or ruining their exit with poor financial stewardship including down rounds or bridge rounds
Always time to fix it later vs taking the time to plan and execute correctly in the first place. This is a relative scale of time to market and risk to opportunity cost but with the exception of large events like tradeshows or such a few more weeks to get it right is better than hobbling along with literally millions of dollars of technical debt if success is found.
And re:tradeshows - demoware is the name of the game and sales needs to be onboard with eng that demoware is demoware and what to sell ahead of the product
Lack of clear execution plan as product market fit is found and everyone has been acting in "throw shit on the wall to see what sticks" mode
General lack of discipline to keep things orderly as work is done which is a failure to understand systems and second / third order effects. Speed is a lagging indicator not a leading one. Everyone wants more, faster but then fails to slow down to put process in place to facilitate moving faster.
Not growing teams appropriately. Lots of lack of empathy, poor hiring practices, abysmal firing practices. Lots of tolerance of "smart assholes" in small teams when leadership only cares about P/L and so the toxicity grows.
