Earlier quoted context omitted.
Quants build models using math far beyond what an undergrad learns, including tools such as martingales, stochastic calculus, Black-Scholes (and vast generalizations), Brownian motion, Stochastic differential Equations, numerical methods You absolutely don't need a PhD to learn those things. Black-Scholes and Brownian motion was covered in my undergrad courses and the rest of the topics you mentioned where covered in…
>You absolutely don't need a PhD to learn those things. True. You can learn anything without a PhD. A PhD requirement reduces the cost to hire qualified people. Instead of having to pay to interview 1000 people to get 5 you can interview 20. Companies recruit PhDs because they have amassed many techniques, and have modelling skills on average that are better than non-PhDs. There's also quite a difference between seei…
While everything you say is no doubt true, I've got a a lot of friends who have had no problem getting quant jobs in most major finance centers in Europe despite only having Masters degrees