It's an odd concept for sure. People pay extra money to be beta testers for a game company. That's an actual paid career, yet people are willing to pay to do it.
I mean, yeah, for some of us it's apart of the experience to see a game change and grow over time and be apart of it. It's nice when developers respond directly to you and even take your ideas into consideration. It's nice being apart of a community, too
I get this if we're talking AAA millions of dollars dumped into a game and it goes early access, but EA indie games have been a blast for me for years.
Most of the EA games I buy (not all, but a significant majority) are sold for less, sometimes a lot less, than their final sale price, and I get tangible input on the design decisions before 1.0. I'm a big fan. I get to provide funding and feedback to a game I'm excited to see, get it for a good discount, get to see it grow up, and then when it blows up and everyone loves the game I'm considered a source of arcane ancient knowledge about it. It's fun.
Mostly I enjoy being able to go on a game forum and say "this sucks, we should consider changing A to B" and then logging in next week to find B implemented.
Yep, it really comes down to knowing you're buying an unfinished project that has the potential to never change from its current state. Never buy a game based on the promises, buy it based on whether you'll enjoy it now. It also helps if the dev has a good track record of releases. Things like valheim and palworld im OK with buying because even if they never change, I still had many hours of fun with them for the price.
To be fair, early access feedback is very different from beta tester feedback.
Beta testers focus on tangible actionable feedback, like: "game crash in x situation" or "y character's arc could use restructuring". Whereas early access feedback is more like "these parts just aren't fun" or "man, i, j, k, l, & q would be so cool!", which isn't nearly as actionable, but arguably more useful to the end product. Though good luck bug hunting with "game bork pls fix".
At the same time, beta testing isn't fun, it's work. Trying every combination of buttons to find edge cases can be mind numbing, and playing the same thing 400 times in one day can drain any appreciation of the game as a whole. Early access players can actually play the game, and leave if it's not fun. The majority won't even leave feedback anyway.
Also, beta testers often need to sign NDAs and could loose their career by breaking them, while early access is straight up letting the cat out of the bag. Depending on how replayable or spoilerable the game is, that might be undesirable.