Facing a potential health crisis without insurance has got to be one of the biggest disincentives to starting a business.
Even if that disincentive is irrelevant to most entrepreneurs, you still have potential entrepreneurs with health issues. If X% of potential entrepreneurs have managed but costly health problems, the disincentive to starting a business must be much higher.
I know a few such people myself, and I don't even really know that many people. One category is people with issues from birth: one friend of mine has a congenital heart defect, which is well managed, but completely disqualifies him from buying health insurance on the open market as an individual. So he is basically forced, against his will, to work for a large corporation, so he can qualify for their group health plan. Note that this is due to something that happened before he was even born. To me, that's not how things should work in a country with real individual freedom and equality of opportunity.
You misunderstand individual freedom. Freedom, in the context of a "free nation", isn't freedom from consequences or risks (even those out of a person's control), it's freedom from the imposition of state-sponsored force. This is an important distinction. We all invite a little state-sponsored force into our lives (i.e. the persecution of violent crimes, the civil court system, etc). Your version of "freedom" actually requires state-sponsored force at a fairly low threshold: if someone can't pay for their own health insurance or medical bills you're going to force others to pay it for him. You're not asking for voluntary donations, you're taking with the threat of legal consequences. That can't be congruent with any meaningful definition of freedom.
It is you who misunderstands individual freedom. Freedom is not some formalist anarcho-capitalist construct, but meaningful ability to take individual action. That requires, as Hayek argues, that a functioning state exists, which provides basic physical safety, a minimum of economic security, and contract enforcement, within which people can act as individuals. Absent that, in the "state of nature", people are forced to cling to tribalist groupings (religions, extended families/clans, etc.) for security and coverage of the "risks common to all", which is not individual freedom but collectivism.
You're not really illuminating much by explaining with the contorted libertarian definitions of 'individual freedom'. Seriously, you can't think of a 'meaningful' definition of freedom that includes helping each other? Not necessasrily one you have to agree wtih, just one that is 'meaningful'?
I am in a similar situation. I have thyroid cancer, which is generally a manageable form of cancer but has a small (but not insignificant) risk of recurrence and distant metastasis which could require expensive diagnostic & treatment options. Having a pre-existing condition makes it very difficult to buy insurance on the private market and it is very expensive, if you can buy it at all. I recently hit a point in my life where I'd paid off debts and could have afforded to take a risk and start my own business (and want to), but I am not willing to put my family at risk for bankruptcy if I end up requiring expensive tests and treatments and I'm not willing to forgo those things and risk my own life. My dad faced a similar situation when I was younger. My mom was diagnosed with cancer at a time when he was considering leaving his blue collar job to return to college; he ended up staying in his job to keep his generous union health care plan, my mom got great care and eventually recovered, but he missed a chance to grab new opportunity because the risk again was too great.
Even if that disincentive is irrelevant to most entrepreneurs, you still have potential entrepreneurs with health issues. If X% of potential entrepreneurs have managed but costly health problems, the disincentive to starting a business must be much higher.