You said it right - the number of PEs and CTOs are a lot lesser than bankers, and naturally as a result millionaire employees among them would be lesser. This is a simple case of maths.

The focus now is on, why is banking so highly glamorized? Answer - because with banking you can achieve instant high gains due to commission (and for that matter, any sales job) Not true for engineering jobs, where you have to work your way up steadily. Youngsters nowadays look at fast gains and results (just look to the slimming centres nowadays - who needs exercise? But it is well known that exercise is the best way of losing weight)

And I also know a fren who's an electrical engineer - he works for a US company and takes home a 5 figure salary too (in USD) but he's singaporean. And he is not even 30.