My father is an economist and voted for Republicans when the GOP was the party of conservative spending. He has been voting third party for a while now because the GOP became totally fiscally irresponsible, whatever they claimed. Now he is going to vote for Biden. That's largely because he is offended by Trump's racism, corruption, and abuse of power, but also in part because he thinks Trump's mismanagement of the pandemic will hurt the economy, including retirement accounts, in the long-term. Carl from the first letter is delusional and likely using the stock market as a fig leaf to cover for his identification with Trump's tribe.

I'm not sure what I would advise LW1. She's not in a relationship with Carl; she's in a relationship with Carl's son. I don't think a conversation with Carl would go anywhere helpful. I am, at least, glad she's getting this insight before the wedding.

The boyfriend from the second letter also identifies with Trump's tribe. He wants white men to hold on to power; Biden, although a white man himself, has strongly signalled he plans to include other people. The boyfriend couldn't give an answer about why he prefers Trump to Biden because he hasn't even created a fig leaf. Get out now, LW2.