This is because most people think that Congress/institutions as a whole are dirty, but ask them about their congressperson and support shoots up significantly.
If we can’t analyze our own choices as potentially contributing to the system, including not voting (which is more of an endorsement of whatever happens rather than a denial of approval), then we cannot move forward.
Is it not? The US doesn't require minimum turnout for elections, so not voting just amplifies the power of the people who actually vote. It is in effect a tacit endorsement, unless you're trying to effect legal or regime change in addition to not voting.
As far as "my vote doesn't matter", this is quite silly considering how the last two elections featured electoral votes won by ever thinner margins, and that even at the presidential level with the highest turnout most people don't vote, to say nothing of state local elections, primaries, etc. https://i.redd.it/p0z5srsw7py51.png
If we can’t analyze our own choices as potentially contributing to the system, including not voting (which is more of an endorsement of whatever happens rather than a denial of approval), then we cannot move forward.