Also, if it's anything like Pathfinder there is a vast resource of free monsters and rules that allow anyone to quickly assemble campaign materials themselves. Alternately there are third party adventures as well, though many are also behind paywalls on Patreon and other funding sites to, you know, compensate creators for doing the work.
FWIW, it's not a starter set, it's a playtest. It's stress testing things, and leaning on Pathfinder assets. You're not missing out on the full meal deal right now.
I feel like that actually makes it worse. Making people pay to be playtesters? Last I knew playtesting was a job.
I haven't really looked into it at all because I'm not interested, but do they at least state that you'll get the updated material that you paid for when it releases?
I know some of the union leaders at UPW, including one of the Paizo writers that may have worked on the starter adventure (I don't know for certain). They're incredibly passionate about their work, and honestly would understand your frustrations about capitalism. They likely pushed to make as much as possible free, so folks in your position would still be able to share the joy of their work even if they can't afford the starter adventure.
I know none of this will make your frustration go away, but I hope you know that they didn't do it out of malice.