If they want to "share with society", it's nice, but they can do it after taxes, just like everyone else.
Even if a rich person reinvests everything, the control over large amount of money is what makes it problematic.
Also the idea that welfare doesn't go to investments is wrong. When you buy groceries (or anything really), there is a decision made by the management of the company you buy these things from to reinvest part of it to maintain or build productive capacity.
There is no need for a "capitalist" (owner of the enterprise) to insert themself into the process, they are useless middlemen who get a cut, essentially. (They are not so useless when they do actual managerial work, but then they can be just an employee like everyone else.)
> Even if a rich person reinvests everything, the control over large amount of money is what makes it problematic.
What about the control that out-of-touch politicians and bureaucrats have over large amounts of taxpayers' money? Shouldn't we find that far more problematic overall?
> There is no need for a "capitalist" (owner of the enterprise) to insert themself into the process, they are useless middlemen who get a cut, essentially.
Then why do newly created enterprises almost universally seek outside capital investment? Sounds like there is a need after all, otherwise you could just have a partnership structure and take no outside money whatsoever.
What's your solution to the local knowledge problem? Capital markets are like other markets. Capital gets allocated to where it's needed, holding aside market failure (which is what regulations are supposed to fix). Capital owners seek out the best return/risk, and because they are on the ground and diverse in views and skills, that solves for the local knowledge problem.
This is where startup seed funding comes from, capitalists like YC who are good at it rather than some incompetent. It's why bad companies eventually lose the ability to raise, freeing up societal resources.
What appears to be implicit in your comment ("There is no need for a capitalist") is an advocacy for central planning for capital. Although you also say "they can pay taxes" so maybe that's not what you're advocating for.
If you want to know what I think is best, it's possibly a wealth tax applied on global wealth, along with stronger regulations around media concentration, political spending, and a few other things. But to eliminate capital markets and push it all into a central planner is bad.
You could always replace him with a "banker" who instead loans you the means of production on credit, but nobody is going to make you a lathe for free out of the goodness of his heart, nor buggies for your grocery, nor the produce for your shelves and meat for your coolers. The banker makes you take the risk because, if it fails, he probably takes your house.
Believe it or not co-ops exist just fine and some do very well. It sounds like what you would like is a co-op and I will be quite happy for you if you start one.