Typically you show up where you think its close and you can turn a state around. Hillary (because of suppression polls) thought she had Wisconsin and Michigan locked up. She lost those two states by less than 40k voters. That's an FIU football game in states that large. The AA community that voted in record numbers stayed home. 100's of thousands of votes in high voting areas never materalized. Had she done a few more visits, had she thought it was close, she would/should have gone there.
Trump in Florida, Trump in NC, is Trump conceeding those states are close. He's not making the same error she did, he's not going to lose them because a few folks state home. The fact that Biden is in GA and Kamala is in TX demonstrates he believes those states are also in play.
We'll know it all in a few more days. I don't think either side will stay home this time.
There are more Dems than Trumpers but Trumpers vote higher than Dems ever will. Question is what do actual Republicans do. How many vote Dem instead of Trump. That'll be the margin.