Couple things --
Bill Gates is obviously a smart guy and has smart guys around him. He's a big time philanthropist and he spends a lot of money making social improvements. I imagine he's considered this food co-op possibility and maybe he's just come to the conclusion that that's not the most productive use of his money. Or maybe as a big time capitalist, he doesn't see productive value out of socialistic "communes" as it were. Maybe he thinks that's "building down" rather than "building up".
The reality is -- our existence is based on a limited resource environment. As a consequence, all living things try to conserve energy, e.g., humans are lazy as a biological fact. If you build a system from communal sharing and minimal effort, that system is destined to end in scarcity of resources because people inherently don't want to work.
If you incentivize hard work there will be excess productivity because some people will work hard to receive the corresponding rewards. But you'll never be able to incentivize everyone because some people are more committed to conserving energy than others. But, socialism rewards laziness and laziness is unproductive. So maybe that's why Bill Gates doesn't bother with it.
And the second point -- I don't think you get to be a billionaire without being a serious asshole. You have to shamelessly self promote, you have to lie and cheat, coerce, bribe, humiliate -- I don't think there are any "nice guys" at the top of the heap. There are no "nice" billionaires.
As an example, my business has failed because I'm not like that. Marketing and promotion is basically being a loud boorish asshole in a party, except in a business. I concentrated my efforts on being "the best". The best has NEVER succeeded in business. Only the best at MARKETING. The loud obnoxious screaming fucking assholes that you're entertained by and go to because you can't avoid them. I entertain too much human dignity for that, consequently I sit and make angsty comments online all day.