Let's say you're being paid $1k per month by your job. You would say you receive almost nothing, right? Simultaneously, you would also say what you do get is essential to your livelihood. Same here, larger scale.
That's not an accurate analogy if what you're saying the $1k/month is your entire pay.
More accurate would be saying I make a $100k/month of which $1k comes for a certain source, and then me saying that thousand is essential to my livelihood. I'd be lying if I said that; I make a whole lot less than $100k/month and I could easily forgo $1k/month today which just goes into my savings anyways.
It's disingenuous to talk as if the relationship to NPR content to their funding is some simple linear relationship.
Every penny of their income is important. If they had less content to provide to member stations, those stations would have less content and would pull in fewer donations. It then becomes a death spiral since less content results in fewer donations.
While federally originated dollars are a small portion of NPR's total income they're not unimportant since they can't be replaced by other sources. A 1% reduction in income means they need to reduce expenses by 1%.
In your analogy, $1k/month goes into savings. Losing that wouldn't break you financially. You're not spending your all of your income. If you were you'd need to cut your expenses by the $1k/month. In that case you'd consider that 1% pretty important.
What's there to address? 1% stable funding is still 1% you can rely on, just because you receive additional funds from private sectors or alternative sources that are unreliable, doesn't negate this. You can literally see this in CPB funding, where private sources are incredibly variable, and that is what CPB gets, NPR is only allotted a portion.
Hope that helps you visualize the situation.