This assumes how much of the founders' shares they sell and the size of the raise. The $400k figure is just arbitrary here. I imagine when companies are raising Series B or later, founders are walking away with millions.
Even that averages to a senior Eng salary for the very very few founders who get there.
This has to be tempered by other realities - no social life - working 80 hours a week easily - risking personal finances - health problems - good chance of divorce / no deep relationships
Starting a company is no joke.
Very few get to series B/C.