Maybe determine how much money the families need to have in order to spawn entrepreneurs? I suspect that number isn’t $100M, but more like $10M. Then, change the tax policy to create 10 families with $10M instead of 1 family with $100M.
As noted by others in this thread, starting with entrepreneurship is a combination of knowledge, skills and somewhat being financially independent enough to commit significant amounts of time to creating something from scratch and - most significantly - having a network to achieve the latter.
Creating opportunity is a systemic, complex and long term challenge that you can't simply put a $ amount to. Your surroundings and upbringing shape you massively and there is no money which can make up for that and time. When you're 25 coming from a dirt poor community and are the first to study in your family there is such a slim chance you have seized dozens of opportunities correctly so that they stack up to put you in a spot where you are not only able to (aka resources present) but capable of achieving successes comparable to privileged peers. Network and skills are essential. Highly recommend reading "Cities and Ambition" (http://www.paulgraham.com/cities.html) for more context.
I guess what I'm trying to say is that the old Chinese proverb "Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime." is true when it comes to creating opportunity. It's not a "point in time", but a continuous problem.