"Rich people vote their self-interest in every single election. Why don’t poor people?"

For more than two decades, Edwin Lyngar voted wingnut. Though government programs like WIC (Women, Infants, Children) and EITC (Earned Income Tax Credit) were the only things enabling him and his wife to balance their budget at the end of the year, Edwin hated government.

At 20 years old, the college dropout had joined the service and married a pregnant 19-year-old fellow dropout. The young couple found themselves in severely straitened circumstances and in desperate need of help. They accepted WIC vouchers but, after waiting a long time in a long line for Food Stamps, they never made it to the head of the line. Deep feelings of failure and shame prevented them from securing the assistance for which their circumstances qualified them.
That, says Lyngar, is what damns poor repugicans at the ballot box – deep feelings of failure and shame. In his words:

I felt my own poverty was a moral failure. To support my feelings of inadequacy, every move I made only pushed me deeper into poverty. To make up for my own failures, I voted to give rich people tax cuts, because somewhere deep inside, I knew they were better than me. They earned it. My support for wingnut politics was atonement for the original sin of being white trash.
I ignored my own personal struggles when I made political decisions.

So Edwin continued to vote repugican. He voted the shrub in 2000 and 2004. In 2008, he voted libertarian "even though the utter failure of the free market was obvious". In 2010, however, he found himself unable to support his own tea party candidate. It was Sharon Angle, whom Lyngar describes as "an obvious lunatic". Instead he contributed to the Rand Paul campaign. He says that within months of the tea party victory, he realized and regretted his mistake.

I could only watch as the people I supported inflicted massive, unnecessary pain on the economy through government shutdowns, spending cuts and gleeful cruelty.

That was the turning-point for Edwin Lyngar, the moment when he finally "got it". In 2012 he voted to re-elect President Obama while wishing there'd been a major party even more liberal than the Democrats. In so saying, Lyngar wasn't voting against wingnuttery but for liberalism. It wasn't a backlash, it wasn't revenge; it was an awakening. After a 20-year nightmare of misguided shame about being poor, of voting against his own interests, Edwin Lyngar woke up and became a committed liberal. There's a keen irony in that his circumstances today are so much better in every way. After gaining his Bachelor's degree (free, courtesy of a federal program), he then used the GI Bill to get two graduate degrees. Both he and his wife are now professionals enjoying the comfortable middle class lifestyle they could barely afford to dream about when they were struggling.
After more than 20 years, Lyngar came to the realization that it was liberals who made his journey possible, not wingnuts whose policies threatened his livelihood and family's security every step of the way.
Edwin Lyngar's story can be found at Salon in Why I fled libertarianism — and became a liberal and I was poor, but a repugican cabal die-hard: How I finally left the politics of shame. He concludes the latter article with:

I wish I could take the poorest, struggling wingnuts and shake them. I would scream that their circumstances or failures or joblessness are not all their fault. They should wise up and vote themselves a break. Rich people vote their self-interest in every single election. Why don’t poor people?

In relating his own history of ingrained wingnut thinking accompanied by feelings of failure, guilt and shame, he answers that question with profound insight.