The first reason is to sow more division among Americans. The chaos theory works (or at least they think it's working) for those invested in power/money/influence and desperately want that power base back in their fold. Dragging their feet on the vaccination program will (from their viewpoint) make Biden's economic recovery slow, sluggish, disappointing. They have no problem killing off Americans, preferably Democratic Americans, but even their own supporters if it produces wins in 2022 and 2024.
However, Biden's infrastructure and American jobs program which looks likely to get through reconciliation will have a massive, transformational effect on the country's economy and Americans' welfare and well-being. Add that to the Child Tax Credit already being distributed and I believe that the train is on the track and will run these suckers down.
At some point in time, sooner rather than later, Red America should be waking up to the fact that their GOP 'leaders' don't give a shit about them or their families, have lied to them from the start and are quite willing to let them and their kids die. The fact that younger patients are ending up in hospitals with the delta variant may turn the tide. You might be ridiculously arrogant and defiant yourself, but it's pretty hard to watch a child gasping for breath or ending up on a vent because you didn't see the need of vaccination.
The Republican elite class and their mouthpieces aren't simply crazed ideologues. They've really taken the path to the Dark Side.