I've been doing contract work for the last 6 years. In the markets I'm in Dallas and Chicago for my skill set (18 years) i'm finding it easy to find jobs at $125/hr but not much more than that. Even at that number I get lots of "thanks but no thanks." My most recent project, Apache Kafka and Spark, is only $115/hr. Which is close to $250k/yr but not any where near $400k/yr. I'm wondering where you're finding clients willing to pay this much and what type of work are you doing?
I personally value the autonomy over almost anything else -- I can live in a low cost-of-living city with my wife for half the year, go skiing/mountain biking over lunch, and overall spend more time among the people I care about. But that does come with all the stress of building a client base, chasing down payment, explaining to non-technical people why their ideas aren't feasible and I can't build Siri in 3 weeks, etc.