True, but how much does this really matter? Milliken argues that it barely matters at all and so does Swindle who claimed he makes most of his revenue from FB if I'm recalling correctly. At the very least it's hard to prove ROI without affiliate links or codes linked to the endorser. But that's in-the-weeds stuff.
Here's the bigger picture. I watch fishing tournaments, but nobody in my circle watches pro fishing tournaments, not even my brother. Nobody I know of outside of my immediate circle, and I know a lot of people who bass fish, watch pro fishing or even follow it with the exception of one kid. He actually chose a college because it has a fishing program. All of these guys are obsessed, like really obsessed, but they could care less about the pros other than the kid. They know a name or two, but that's it. Also, I know of none who are regulars on any fishing forums. They get their info from YT and perhaps from some specialty forums on FB or local FB groups. Few are regular participants in any group. They get whatever info they need, and they're gone. Very few are active.
Regardless of how many fishing licenses are sold each year, the audience for pro tournament bass fishing is clearly very small outside of the people who do it, their families, and perhaps some of their friends. Look at the weigh-in audiences, when they happen to show them. The Classic is an outlier.
That's why pro bass fishing is cash poor. Most people just don't care about it. Some will care more with someone like Milliken coming in, or the next Milliken-esque YT star who's up to scratch and can qualify because they'll bring their audiences with them. Their audiences will buy the stuff they promote, and those sales will be measurable as will the watch time for tournaments. I'd bet nothing drove last year's Open's numbers more than Milliken's audience. The site crashes during weigh-ins were ridiculous and annoying.