I mean, it's their job. Just like any other job self-employed job, you need to invest time and money into it to see a return, work out partnerships (in their case with sponsors), and be sustainable and also eventually end up among the invited media with Disney and potentially Universal, Sea World, Six Flags, Knotts', etc.
Just like any other well paying job (the big vloggers/influencers do get paid very good), you have to put in effort to get rewarded. So while you see it as a waste of time/life since you assumably aren't doing that stuff and just go to the parks to have fun, for others, it's a way of life and how they pay their bills and provide. It's also not an easy path to choose, especially if you want to be a daily vlogger, as many feel as if they always have to be "on" since they're always filming parts of their life. To me, it seems like something that would make me incredibly jaded with the parks so it takes the right kind of personality to succeed.