[resters]

How many of the workers chose to work there instead of some other, inferior option? How many are proud of what they accomplished? How many went on to found other successful startups like Instacart?

selfishness is allowed? Is it possible to disallow a core human trait?

[pedromsilvapt]

Yes. Envy is a core human trait as well. Some people envy their neighbor's car. Stealing it is still forbidden by law.

Likewise, disallowing envy (or selfishness) by itself is not possible, but making illegal the actions that result from those feelings can (and sometimes should) be outlawed.