What will change once "alpha" ends and the game is supposed to be complete? Since when do you have to pay for becoming an alpha tester?
There's a bright blue box with larger font right in the middle of store page that tells you it's early access... you can't miss it.
What changes is no more updates.
I prefer to think of it as I purchased the game ahead of time, and at a much cheaper cost. I got this for less than $10 back when I bought it.
I bought three more copies over the summer sale for friends. It was -66%, so somewhere around $8.50 per copy.
A game worth hundreds, if not thousands, of hours of entertainment for the cost of lunch (a cheap lunch).
Nobody forces me to play my early purchase. I could just set it aside and wait until it's done... but I prefer to watch the game evolve through the years. I don't own a ton of games... about 50, and I would say about half of those are early access. Some I haven't even launched yet, but I picked them up in their initial days dirt cheap and I know they will be worth the money when I do play them. After all, if I pick up a game for 10 bucks, and all I get out of it is 10 hours of gameplay, then $1/hr of entertainment is worth it. Very few of them have I paid more than $10 for and those are AAA titles that I have loved for years such as DOOM.
Another thing that I expect would change is the cost. It's 25 bucks right now I believe. I wouldn't doubt that at the time of release it goes up to around $40 for at least a year afterward. When that happens, anybody buying it at full retail cost can be assured that the likelihood of the game being good is much greater because it went through years of actual players playing the game before it was officially released. So, even then, it will be worth the money. People spend hundreds of dollars every year on cable TV, renting and buying music and movies, and even going to theaters to watch movies. The cost of this game and the hours you get out of it is huge in comparison to these other sources of entertainment.