How does freelancing income compare to working as a senior engineer at a big corp ($300k total comp if you include bonuses, benefits and subsidized health insurance)?
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.
Edit: My point is that freelance work income may not compare, but the income may not be the reason for moving to freelance. The op did not explain why he moved to freelance, but I can think of some great reasons to do so.
If I didn't have paid vacation days, I doubt that I'd ever take one. They'd simply be way too expensive. It's one thing to use paid vacation days, another thing entirely to give up over a week's worth of income. I don't think I could do it.
Top independent freelance software developers can make $300k if they work hard and have a good network, as can top big corp engineers. Of course, neither is easy to achieve and the metrics are different. (Freelancers are valued on their results, big corps hire on pedigree and games.)