In feudalism the taxes go into your lord's pockets. In democracy you get to vote on how taxes are spent.
https://www.aclu.org/news/civil-liberties/block-the-vote-vot...
The fact that self-interest may play a role in the careers of many politicians doesn't undo the damage that this attitude has caused to our polity.
"They're all fuckers, they're the same" is the attitude that leads to people being unable to differentiate between one party that is subject to excessive corporate lobbying and donations, still starts too many wars, and frequently makes mistakes but nevertheless is fundamentally trying to improve most people's lives, and another that wants to destroy Medicaid.
I prefer to judge my political opponents by what they actually do, and by that metric, it is self-evident from both their public and private speech, and from the legislation that they seek to (and sometimes do) pass, that Republicans would like to destroy (or at least massively downsize) redistributive programs that provide assistance to the poor.
Now, as to why they might want to do this, I remain mute and disinterested, since in 61 years of life, I've never heard any explanation that doesn't deconstruct under cross-examination.