That kind of advantage for Dems is unsustainable.
And, the last I checked the RNC was setting fund raising records and the DNC was trying climb out of debt.
The DNC and RNC don’t themselves really spend that much. Campaign committees and PACs are increasingly where the money is.
PACs are more favored by donors because the donor retains more control over spending.
Here’s an article noting the various groups’ ad spending in this election:
https://www.nbcnews.com/card/updated-ad-spending-pa-18-11-7-million-n855256