I don't want to get the site in any copyright trouble, but if you do a Google Image search for "trump boat rally south carolina" it's clear that it's not just some old Boomers.
There are flags of every type, massive flags, in some cases pasted on like butter, Trump swag of all kinds, Trump towels, Trump bathing suits, entire boats painted "Trump." No matter how big a lead you think Biden has in the polls, you have to admit that he could never get enthusiasm like this. That is why I still can't see him pulling it off. Heck, I'd be impressed just to see a Biden bumper sticker or yard sign.
Thats because most of Biden's support is anti-trump rather than pro-Biden, while the opposite is true of Trump's support. That being said, many polls actually find that Biden supporters are *more* enthusiastic to vote than Trump supporters.