I don't follow American news enough to confirm your claims. But I'll take your word here.

The problem is that 80m Americans did not vote last election. If 10m of them had voted for the D side, this might have chastised the Republican Party enough for its to reconsider its leader. That's what happened to Nixon.

My political crystal ball (which has been wrong) is that the D's are bleeding soft support for both 2022 and 2024. All this good work is likely to become undone again.

What's the solution to getting more of the 100m non-voters to truly analyze which party is indeed better for their own self-interest and cast a ballot?

If they are not exercising that power for their own self interest, then, to me, that's another sign of a broken democracy. Try to see things from their perspective.