If by "investment capital," you mean money, rich people don't produce money, they accumulate it. Money would exist whether rich people existed or not.
Suppose a rich person dies. Does his money die with him?
You don't need rich people to have money, any more than you need one person to have all the apples in order to have apples.
The wealthy are people who have accumulated enough money to feel secure with the possibility of losing a portion by investing it in new business or a business expansion.
Risk capital, venture capital, investment capital, whatever you want to call it...I can't risk it, and neither can you...but the wealthy can...because they have a secure cushion to fall back on.
Without that capitol, the economy grinds to a halt.
Is that so hard to comprehend?