Regarding Wall Street full of PhDs.
If they have PhDs in Engineering, Physics, Mathematics, etc., then none of these folks were achieving tenure, working for corporations in SV [where stock options and salaries put real talent in the tens of millions and then some] or actually recognized by their peers in whatever field they so choose to do their research.
As a Mechanical Engineer with CS degree I worked with PhDs at NeXT and Apple from Astrophysics, ME, EE, Pure and Applied Mathematics [crypto, algorithm theory, etc], etc., but most of them with rare exception weren't the giants at NeXT or Apple.
During my undergrad days both the Physics and Mathematics departments notoriously have a hard time filling out their departments in certifications. Not because they turn people away. It's because the best mathematicians become Engineers whether it be EE, ChemE, ME, Materials Science Engineering, etc., who want to work designing chips, work with MEMS, Nanomaterials, etc.
They don't want to just work in Particle Physics or attempting to carve a nitch in most of pure and applied mathematics which has already been done.
Most of the software developed is not by in-house PhDs who wanted to strike it rich with Wall Street. It's outsourced.
My developer list for Professional Services always included Merrill Lynch, Fanni Mae, Swiss Bank, etc., who were contracting out NeXT/Apple consultants and in-house Enterprise staff to develop their Enterprise Solutions.
Sun Microsystems was a huge shop at doing this, not to mention Oracle, Sybase, etc.
Most of the development is done by 20+ year architects of n-tier mission critical software, not a bunch of bored PhDs with Physics and Math degrees. This myth continues to perpetuate itself. Wall Street is not teaming with the smartest groups of folks. They are teaming with the largest unethical groups of folks. Mostly business and law majors.