Shutting down the primary business happened, because it couldn't be sustained any longer (spare me with the few days the remaining BTC could've bought...).
The lack of capabilities in running a business became transparent, because Nu didn't have (and still doesn't have) transparent accounting. The first months or even quarters, which have been very expensive are hidden from the public.
This lack of capabilities caused the fall of Nu.
This still is the main problem.
Liquidity operations used to be centralized in the beginning.
They were made decentralized after exchange hacks.
The true cost of that was never evaluated.
I've found an interesting thread from earlier this year regarding what you seem to propose (a thread worth reading in my opinion):
How come this liquidity operator, who seems to have decent knowledge about liquidity operations got chased away?
Was it, because he dared facing the truth, before others did?
Was it inconvenient to see the dream of the Liquidity Engine questioned?
You realize why I called it Ponzi Engine?
I will continue to do so, until a sustainable way of operating it was found.
Good idea, but don't give the control to the wrong sock puppets. There's been enough damage relying on the wrong people.
Reserve can't replace revenue.
The bigger the reserve, the bigger the tank.
This tank still needs refill, if you don't want to see it run empty.
That refill needs to come from revenue and not only from new money being put into Nu, because that makes it a ponzi scheme and the Liquidity Engine a Ponzi Engine.
There's no reporting from the first quarters of Nu's existence (and some months before the official release). They've been quite important ones. A lot of money was paid for development and liquidity back then