My wife and I are college educated and as late 40's as you can get. Total equity investments (not including cash or home equity) are at $8.4 million right now. We have about $300k in cash investments or cash equivalents. Income is between $700k and $850k a year depending on how our companies do every year.
Our plan is to retire in 6 years @ 55. Our home is worth about $1.2m and we owe $270k which will be paid off in 6 years at 2.75% apr. Our kids college education's are paid for already in 529's.
We could end up inheriting another $1m-$2m but aren't counting on it.
I think if we have another $1.6m in investments in the next 6 years, we'll be fine putting at a nice $10m round number. We live well and are blessed.