In states which are governed by Democratic machine politics, such as California, (a) money gets diverted from actually doing things, like building high-speed rail, to paying off members of the political coalition, often indirectly, and (b) there is a lack of agentic action, so even if paying off groups isn't the intention behind wasteful policy, no one will come by to correct the policy to make it less wasteful.
As a result, the ratio of money spent to things actually produced gets worse.
This should be expected to make taxpayers rationally more likely to oppose paying more taxes. At the same time, since the government sometimes does need to actually do things, or would provide a benefit by provisioning public goods, it increases the amount of government debt taken on relative to the amount of public goods actually provided.
Part B is, ethnic conflict, mass migration, and machine politics are all known to go together.
Ethnicity creates a credible axis to signal affinity to, to create an outgroup to take resources from, and an ingroup to give resources to, such as in the Curley Effect. It's very difficult to change one's ethnicity, if it can be done at all.
As for mass immigration, in Machine Politics in New York City (1886), Theodore Roosevelt noted that there were many immigrants in urban political machines at the time, which was one of the previous times we were dealing with them. It's my belief that prior generations of Americans cut off immigration not merely out of "irrational bigotry," but partly to get control over nasty political machine behavior.
For an ethnocentric group of new immigrants, the public resources aren't "the benefit or debt that me and my descendants will benefit from or have to repay," but "resources belonging to outsiders, which it is good for me and mine to take and benefit from." The longer immigrants have been here, and the less ethnocentric towards their ancestral origins they are, the more the public budget is "my problem, that my grandchildren will benefit or suffer from."
Have you ever noticed that under SJ discourse, SJ is conspicuously excluded from ever having to provide any measurable benefits, while the targets of SJ are subject to unlimited moral claims on their rights and their resources which they are not allowed to dispute? There will always be someone with psychological hangups writing something like "white fragility," but while the reasons such a thing spread are complex, as a coordinating basis to make unlimited claims against an outgroup, while avoiding all accountability whatsoever for the ingroup, there are reasons for members of a political machine to platform and spread such rhetoric.
A nation is a large, thin network. A nation is really, really big, creating lots of specialized positions of labor for its operation and maintenance, and relying on reliable enforcement of rules because the feedback loops for those positions are really long.
A tribe is a small, thick network. It can depend on more direct social contact as its feedback mechanism, because the feedback loops are a lot shorter.
It's classic concentrated vs. diffuse interests, as I covered more generally in Great Men Surf the Tides of History.
In the past, machines generally had a party boss, who could rationally limit the scale of taking, but in the past, communications were slow and low-bandwidth. It is my belief that the Democrats from 2014 on are a distributed 21st-century political machine, enabled by electronic communication and social media, which allow them to (somewhat) synchronize their behavior without a party boss to report to.
They pit concentrated interest groups against the larger polity, without someone at the top to cut off the behavior before it turns ridiculous.
Thus, the first step to gain control over the situation is to cut off the supply of new immigrants who are not integrated into the main national network, thereby intergenerationally diluting the concentration of their associated interest groups, and shifting their time orientation towards "this debt is our problem" instead of SJ/decolonization's "this debt is white American colonizers' problem."
By cutting off the supply of new immigrants, Democrats will have to start competing more on governance, and the different factions within the party will have to fight for scarce resources with each other, rather than just relying on a theory of taking resources from the outgroup.
While this will shift their overall ideology to be more normal, and less corrosive, over time, the process will not be instant. It creates more favorable terrain for good people and good, pro-social behavior, but it will take time for those people to fight and to win, and they will have to be provided with tools and understanding of their situation to do so effectively.