Republican lawmakers primarily act in the best interest of the capitalist investor class that donates to them
The Student Loan Asset-Backed Securities market is over $1.5 trillion
They're not opposed to student loan forgiveness out of principle, or just to be jerks for its own sake. It's all about preserving low-risk investment instruments.
Oh, I'm pretty sure the fact that it hurts people is a bonus for them. They get to please their investors and hurt Americans, it's a 2 for 1 deal for them.