You’re assuming poor American working class voters vote against their interests by voting conservative. Leaving aside the social issues for now and looking solely at economic ones, let’s ask the question whether that’s true to them in their own minds.
The American liberal party (Democrats) brands itself as the party that’s going to help you out. It’ll leverage redistribution (taxes) to take money from rich people and corporations and get you stuff like free healthcare, free college, unemployment insurance, etc. That should sound pretty appealing if you’re poor.
However, the American conservative party (Republicans) brands itself as the party that’s going to get out of your way. It’ll cut taxes, remove regulations, get government out of your life and basically let you determine your own path without trying to hold your hand the whole way. Sure, less free stuff than the Democrats offer, but Republicans believe there’s no such thing as a free lunch. Nothing comes without strings attached in the Republican worldview, even if in the Democrat view of course there are no strings.
These two economic angles tap into completely different mindsets.
The Democrat angle taps into two mentalities: “We need to help people out” and “Free stuff? Don’t mind if I do!” The former is the wealthier, more educated Democrats, who feel life’s been good to them and they’d like to see others benefit too. The latter are the poor Democrats, who feel life’s been unfair to them and they could use a little help.
The Republican angle taps into one mentality: “People can make it on their own salt.” If you’re a poor Republican, you just want to be able to live your life without worrying about government handouts with strings attached. The idea of free stuff is a little insulting to you – it implies you can’t make it on your own. If you’re a wealthy Republican, you feel like you got what you got fair and square, and the idea of taking what you’ve earned and giving it to someone who hasn’t earned it goes against everything this country stands for.
You can ultimately boil American conservatives and liberals down into individualists (conservatives) and collectivists (liberals). Redistribution is fine for liberals because we’re all the same anyway – if two people have differing wealth, it’s because of unfairness, and we can use redistribution to remedy that unfairness. Redistribution is anathema to conservatives; it’s insulting to the poor and it’s robbery to the rich, not to mention it upends the profit motive, which in the Republican mind spells bad things for the economy.
I suspect the right answer is somewhere between European socialism and robber baron laissez-faire capitalism, but I’ve always been a centrist myself.
I won’t go into social issues in this comment, since it’s already quite long. However, if you want a better grasp of why conservatives have the stances they do and why liberals have the stances they do, I recommend checking out Jonathan Haidt on moral foundations theory first:
https://en.wikipedia.org/wiki/Jonathan_Haidt#Moral_Foundatio...
http://www.ted.com/talks/jonathan_haidt_on_the_moral_mind
Then perhaps a read-through or listen to Will and Ariel Durant’s Lessons of History (keeping an ear out in particular for the discussion of order vs. freedom, and the integral roles they play in society. American conservatives are pro-order socially and pro-freedom economically; American liberals are pro-freedom socially and pro-order economically).