I think 3 is completely wrong. There's a lot of data out there that says otherwise. First of all, the debt wasn't gained in a linear fashion. It started a rather serious uptick in the 80's and was blown out the water by obama. Probably more important is to look at debt as a percentage of gdp. Post ww2 it was extremely low (comparatively speaking). There was no competition from the outside world to drive wages down or compete with american goods. You can't just say that's illusory. It's most certainly very real. In 1950 21,000 cars were imported. In 1986, over 4 million cars were imported.1. I disagree that libertarianism is an extreme position. Extremism by definition is relative, so as one measure, let's compare remaining candidates in this year's race. If you added Libertarian nominee Gary Johnson into a debate with the most popular 5 mainstream candidates in this year's election, Clinton, Sanders, Trump, Cruz and Kasich, I guarantee Johnson's platform and views would appear average or possibly even below average on the "extreme scale" in that debate. And those 5 "mainstream" candidates are even TRYING to be somewhat moderate just to pivot towards center for the national election. Johnson knows he's not going to win, he's not pivoting at all from the same platform he governed from.
2. As I said before, it is not a goal of libertarianism to force equality. I said if it happens as a byproduct of policy (or lack of policy), then fine, but it's not a goal. Regarding libertarians "failing to recognize human failings", that presupposes a goal of forced equal outcomes, which I'm not even sure is a majority opinion/goal across Americans, or if it is, it's not by much. Regardless I would say that those in favor of more power in government fail to recognize many human failings as well, such as the inevitable corruption of power, the overestimation and overconfidence of our ability to control and predict economic outcomes and policy side effects, and an underestimation of the "horizon problem" where someone in office for X number of years kicks the can down the road for the next administration to solve.
People in government are also in aggregate pretty clueless about simple economics. Which is dangerous. For example they'll complain about rising college tuitions, and then propose to increase access to higher education and student loans. Well the rise in tuitions was the predictable outcome of that policy. Or they'll talk about how the middle class can no longer afford to buy a home, but then not be willing to cut the mortgage interest subsidy (among MANY other policies) which artificially raise the price of real estate. They either don't understand basic economics, or they neglect what they know for political expediency. I could list dozens of other examples, and it's not just the Legislative and Executive branches but also the Fed as well.
3. I've never been a fan of comparisons to the 1800s for economics...it's just too different of a world to compare IMO, in almost every way imaginable that would matter for decent comparative analysis. Either way and most importantly I'd argue strongly that the post-war stability to which you're referring is completely illusory. It was in fact simply DEBT that caused that growth and debt that also stabilized the ups and downs (as debt can serve as a short-term stabilizer despite being a long-term destabilizer).
Simple illustration: from 1974 to 2014, all facets of the U.S. (governments/businesses/individuals) took on $58 trillion in new debt, which was a 4.4%/year compounded growth rate increase in debt (not counting inflation, which was another 4.13% during that period...so nominal debt growth was 8.53%/year). During the same 40-year span, inflation-adjusted GDP growth rate was only 2.1%. So JUST TO ACHIEVE 2.1% real GDP growth rate, it took 4.4% of real DEBT growth each year!!! This was factually simply debt-fueled growth. I don't have the pre-1974 numbers in front of me but I will see how that analysis looks post-1937 as well, for a longer-term view, since you had mentioned 80 years. I'd be surprised if it looked much different. Debt can solve a LOT of problems even over several decades, but it can't keep going like this. For a preview, look at Japan--within 5 to 10 years or sooner Japan could be the economic story of the 21st century, and not in a good way.
4. Safety regulation and so forth is not a hot-button issue for me, and as I said before it's a point I'm willing to concede just because I think there are a lot bigger fish to fry. But the point isn't that businesses would police themselves, it's that in a lot of non-critical cases (I'm not talking about nuclear power here), it doesn't take a government entity to carry out the ratings work. This is true today in many industries of course. And again industry has pretty much successfully accomplished "regulatory capture" already anyway. The industries that are getting regulated are often the ones who are writing new regulatory laws, government experts jump into industry and vice-versa, etc.
5. I'm actually not assuming anything about me or anyone else being racist or not racist. I haven't even stated my race, sexual orientation, etc.. I just don't fundamentally believe that a privately funded business should be restricted from hiring or serving a certain class. A publicly funded one should definitely be restricted as such. Regardless I personally doubt too many of these enclaves would arise, any more than they aren't already here today despite government attempts to prohibit them. But even if they are racist and they survive and flourish despite that, that's their business (literally and figuratively), not mine. And as a potential employee or a potential customer, I can choose another business that wants to serve or employ me. In fact if someone wants to discriminate against me it's just as well that they do so in a more explicit way so that I'll realize that's exactly what's happening. Doing it implicitly can be done today.
And to the original number 3, over regulation certainly contributed to the collapse. The government was suing banks to force them to issue sketchy loans. The banks didn't want those loans on their books, so they packaged them up and dumped them off on sallie mae. So how is that not over regulation? Seems quite clear to me. But I was working in the banking industry at the time and saw this first hand. I realize not everyone was. Our bad debt percentages and delinquencies were through the roof.