Nothing that couldn't be addressed, if we turn out to be Sweden. Plenty that won't be successfully addressed, if we turn out to be Venezuela or Zimbabwe.
Given the current competence of our government - on both sides - I don't think we can count on being Sweden.
Should I also bring up the USSR (Union of Soviet Socialist Republics)? (If you're going to claim "that wasn't really socialist", I will not argue, but I will point out that they at least claimed to be.)
Anyway, the point is not that one should cite Venezuela for "any social experiment". One can cite Venezuela (and Zimbabwe) for the position that having the government controlling the means of production often winds up in poverty. (Socialism is defined as "a theory or system of social organization that advocates the vesting of the ownership and control of the means of production and distribution, of capital, land, etc., in the community as a whole", per dictionary.com.) That's relevant because mjevans not only called for the government to spend a bunch of money, but called for "full socialism".
While you didn't explicitly claim Sweden is socialist, I think that may be your implication. Please excuse me if I interpreted you incorrectly.
Sweden (and other Nordic countries to varying extents) are not socialist. They are market economies first and foremost but offer social programs similar to our own that, at least from an outside perspective, appear for more successful in their goals.
Personal views aside (I favor personal freedom and responsibility and the consequences that come of it), the only way I feel you're ever going to achieve any of that here is by addressing human nature. Some subset of the population is only interested in gaining and exerting power over others, others want everything handed to them and don't intend to provide any contribution themselves, another subset wants only to be left alone, and so on. I don't personally see how such disparate views can be reconciled under such a system to avoid the authoritarianism that has always resulted.
I cited Sweden because Sweden is often claimed as an example of socialism working by people who advocate socialism. I will agree that Sweden does not actually meet the definition.
Sweden has never been distinctly socialist. But it used to be more socialist than today. For instance the Swedish government used to own Absolut Vodka from 1917, when Sweden nationalized the alcohol industry, until 2008.
I think the idea may be that human societies (and governments) don't scale linearly. That's at least plausibly true. Is it a large enough effect to be relevant? I don't know.
Or, the idea may be that smaller countries are more socially cohesive (fewer degrees of separation between people), and therefore it's politically an easier sell to ask people to contribute to the welfare of others.
Scale matters. If you don't think so, look at Bubble Sort. It works just fine if you're list size is trivially small. Now try running it on a list with a size > 1 million.
Given the current competence of our government - on both sides - I don't think we can count on being Sweden.