Ask HN: Internal tools should be sold or killed'

A friend is in a weird situation and I didn't know how to advise so I thought I'd throw it out here given I have no experience of this:

-He managed the build out of some internal software used for running the businesses operations

-It has increased the efficiency of business units that migrated on to it but Azure bill has scaled up too

-CEO of group has sunk the build cost into it and wants it to yield

-It was designed with a lot of input from CEO of the group who wanted it do very specific things

-CEO of group has been reading a lot about early Bezos

So the opportunity is:

(A) Take the tech put it in a company call yourself CEO and sell it to externals and create a start up. No equity or extra pay at this stage as there is no proof of PMF

(B) Leave and the group CEO will find someone else to give it a go

Has anyone on HN done this and failed / succeeded?

My only advice is if he thinks he has a chance then do it because getting the opportunity to play for free in something few people have exposure to is pretty cool, but get a contract agreed up front about targets and future compensation, and assume it will be the most painful thing ever.

Any thing else?