By my count there were 157 days remaining before the election at the start of June. If Biden raises an average of $100 mill a month for the next 5 months (conservative estimate IMO) that is over $700 mill available or $4.5 mill a day and that's not counting outside groups. Both sides will have more money than they can effectively spend.
This. Fundraising isn't a good indicator of anything except maybe base enthusiasm.