Define a target (say, 1MM), a realistic interest rate, and head over to any compounding growth goal calculator; it'll tell you how much you need to set aside over 10-15 years to hit that target.
To compare meaningfully to startup careers, you need to factor in the premium you pay to work at a startup (in reduced wages) and the very low odds of any given startup making its employee equity liquid.
Generally, the difference between the BigCo path to 1MM and the startup path is that, barring dramatic changes in the nature of our industry (which changes would also confound the startup comparison), the BigCo path is reasonably contingent only on your execution. You can fire on all cylinders in every startup you work at and never end up in the money.