that's likely not even remotely correct. for someone earning in that range, i'd expect more like 25-30% (including health insurance) - should be less if/when you start to work at tax reduction.
I've been solo contracting for > 10 years and have never had to pay anywhere close to 50% in taxes/insurance.
They do play somewhat of a role, but... again, for someone pulling in $72k - even as a single person, they may be paying ~20% of their income in taxes. Assume $12k for insurance - maybe another 18% - this might be approximately 40%.
Married and with kids might increase health insurance, but would reduce taxes because of deductions.
Locality - local/state taxes might increase this - I'm in a mid-level tax state - not no taxes, but not a New York.
Someone earning $72k who is married would have a $24k deduction - they'd be paying taxes on max $48k. MFJ status with no kids earning $72k would be < $6k in federal taxes.
Single earner at $72k - federal income tax in US is ~$8900. It's not nothing but that's nowhere near 50%.
I've been solo contracting for > 10 years and have never had to pay anywhere close to 50% in taxes/insurance.