Everybody accepts drinking coffee or caffeine, but its clearly "performance" improving. There is even a culture of providing adderall to employees if they want. Do investors frown upon those activities?
An openly pot-head founder risks offending or scaring customers or buyers or later investors. It also indicates some who doesn't get the "performative" aspect of being a commodity founder: the expected degree of conformative role playing.
Wouldn't that be putting the company and its management in a very risky situation? Distribution of controlled substances carries much higher penalties than mere possession. If a disgruntled employee calls in an anonymous tip to the cops, they might end up with a bunch of heavily armed cops kicking down their office door. Not so great for productivity...