I briefly looked into this myself ( earlier in my life ) and decided that the "make a boatload and distribute it yourself" method really wouldn't help that much in scientific funding overall . Even if you made 10 million a year, and donated 99% of that, that would only help a handful of labs, which is something. Most science funding is orders of magnitude larger than that, and is on a scale that only nation-states can actually support. IMHO that translates to, if you want to have the biggest impact on science funding (including increasing the amount of funding), the best way would be to work in policy either at the NIH/NSF/etc. itself, as a congressional staffer specializing in science policy, an advocacy nonprofit (such as for a particular rare disease or a bigger, more popular one), or finally as a fundraiser/staff member at an independent science funding organization like the Wellcome Trust, Bill & Melinda Gates Foundation, or more specialized institutes like the Allen Institute for Brain Science.

I don't work in the science-fundraising space, but my gut tells me that now would be a good time to do the last option: with the Trump admin interested in trying to reduce the NIH's budget by 40%, researchers are increasingly looking to non-federal sources of money to continue doing their (expensive) research, like the private science-granting organizations mentioned above. At the same time, there's probably a lot of philanthropists who recognize how terribly shortsighted decreasing the NIH's budget is, and who are willing to contribute more to private science funders in an effort to fill the gap.

There are large numbers, and then there are even larger numbers.

Academic research is roughly $100 billion a year in the US. A foundation with $2 trillion could support that indefinitely with the required 5% minimum distributions. By today's numbers, the seven richest Americans could fund that.

I don't know worldwide numbers, but 4x the US is usually a good rule of thumb. You would probably need the 100–150 richest people to support all academic research worldwide.