At this point it's just brainwashing. Some people's principals are clearly less about their own conviction and treating all this like a sports team. Whoever team "wins", even if the stadium burns down around them.
Another (more charitable?) explanation is they just never make the connection:
> It’s easy to find authoritarians endorsing inconsistent ideas. Just present slogans and appeals to homey values, and then present slogans and bromides that invoke opposite values. The yea-saying authoritarian follower is likely to agree with all of them. Thus I asked both students and their parents to respond to, “When it comes to love, men and women with opposite points of view are attracted to each other.” Soon afterwards, in the same booklet, I pitched “Birds of a feather flock together when it comes to love.” High [Right-Wing Authoritarian scorers] typically agreed with both statements, even though they responded to the two items within a minute of each other.
-- https://theauthoritarians.org/ (2006 ebook)
Conflict of interest by attempting to curry favor for his vanity project by making donations? That's a fair criticism.
Remember that Mexico allegedly would pay for the wall.
So either Trump is doing this officially as a President, but with funding that is illegal/unconstitutional...
... Or the funding is legal, but Trump is doing it as a private citizen, which is a federal crime. [0]
[0] https://www.justice.gov/archives/jm/criminal-resource-manual...
Does Trump paying himself $230 million in taxpayer dollars in compensation for his various criminal prosecutions fit under "waste, fraud, and abuse"?
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