You're approaching the question from entirely the wrong angle. This isn't a moral problem; it's an engineering problem: What kind of rewards need to be offered to founders and investors in order for them to bother innovating and founding new companies? The answer has been worked out many times before--every time a company is started. It isn't fundamentally different, nor more or less just, than the way that the wages of janitors vs. engineers vs. blog authors is worked out. It's just more complicated.
Perhaps legislation could intervene to increase social benefits... but trying to "fix" an economic situation by forcing a "just" distribution of wealth tends to degrade or break the system.
The simple and effective answer is to increase estate taxes. Anybody who tries to get a social-justice movement to focus on any mechanism of wealth distribution other than estate taxes, is probably funded by somebody trying to distract people from imposing higher estate taxes. I'm pretty sure that most of the money for the Social Justice movement today comes from large foundations like the Ford, Hewlett, Packard, Rockefeller, and Kellogg Foundations, which are usually run by people connected to the family in question, with its enormous inherited estate.
BTW, it's pretty unusual for the founders of a large company to get such large fractions of the stock. It probably happens more often in tech due to low startup costs. But even in tech, it's rare. See https://priceonomics.com/how-much-equity-do-founders-have-when-their/ for a list of recent tech startups and how much equity their founders had at IPO. Median was 2 founders who collectively held 15% of the stock.
"How much should they keep?"
You're approaching the question from entirely the wrong angle. This isn't a moral problem; it's an engineering problem: What kind of rewards need to be offered to founders and investors in order for them to bother innovating and founding new companies? The answer has been worked out many times before--every time a company is started. It isn't fundamentally different, nor more or less just, than the way that the wages of janitors vs. engineers vs. blog authors is worked out. It's just more complicated.
Perhaps legislation could intervene to increase social benefits... but trying to "fix" an economic situation by forcing a "just" distribution of wealth tends to degrade or break the system.
The simple and effective answer is to increase estate taxes. Anybody who tries to get a social-justice movement to focus on any mechanism of wealth distribution other than estate taxes, is probably funded by somebody trying to distract people from imposing higher estate taxes. I'm pretty sure that most of the money for the Social Justice movement today comes from large foundations like the Ford, Hewlett, Packard, Rockefeller, and Kellogg Foundations, which are usually run by people connected to the family in question, with its enormous inherited estate.
BTW, it's pretty unusual for the founders of a large company to get such large fractions of the stock. It probably happens more often in tech due to low startup costs. But even in tech, it's rare. See https://priceonomics.com/how-much-equity-do-founders-have-when-their/ for a list of recent tech startups and how much equity their founders had at IPO. Median was 2 founders who collectively held 15% of the stock.