I do understand the difference, but in modern societies, you can't purchase (or sell) equity in a human being - that's called indentured servitude - and despite

I do understand the difference, but in modern societies, you can't purchase (or sell) equity in a human being - that's called indentured servitude - and despite our society having many exploitative employment arrangements, we don't allow total or partial sale of oneself. If you want to take an "investment" of this sort, it would have to taken by an LLC or similar entity, which is by definition isolated from personal liability and vice versa.