If you make 300k while working then subtract mortgage (paid off), retirement savings, child expenses, lower taxes for lower retirement income, you probably only need 130k to have an unchanged lifestyle.
That would require around $3.2 million to fund forever depending largely on the performance of the market in the first several years after you retire.
If you have a defined benefit plan in addition to retirement investments, you might need $2 million or less, depending on the pension payments, to maintain your lifestyle. That's with a fairly conservative 4% withdrawal rate.
Don't get me wrong, I think it'd be great to have more money saved by retirement either to be able to spend more or just be more financially secure, but it's not like you'd be living in poverty on 130k/year with mortgage paid off and kids out of college.
$10 million is probably not attainable for most grads these days because they won't be paid as well as you were and the stock market will probably not return as much as it did in the past.