Thing is, slaves were a big investment, just like today's farmers and machinery: if you didn't take care if it, it would not perform/break down. Now you have to replace it, which costs more money.

Exactly. No one thinks of this aspect. If the slaves were unhealthy, the entire family suffered. So it was to the benefit to keep them healthy and someone content.

Also, some were even treated almost as family, of course that was dependent on the owner.

Read into the true history; it isn't at all like the bullshit they want everyone to believe.

Like the part everyone skips over is that trade started in Africa. Not all Europeans just marched in there and started taking people. For the most part they bought black slaves - gasp - from other Africans.