[wegs2]

(1) In an efficient market, all the companies are one segment are no more and no less likely to be either rubbish or overvalued than any other segment. The risk is random.

(2) You manage that with diversification. I'd never allocate more than 25% of my portfolio to my own active management. My expected returns are slightly higher than index.

(2a) Buying stocks for my employer or their competitors would be difficult for insider trading. I'm much more likely to buy adjacent segments: suppliers, customers, etc. If I'm picking a supplier, I'm uniquely qualified to have alpha on their stock. On the other hand, my own job isn't very exposed to market changes in those segments.