1 - you pay full price on steam and dont get full game
2 - you pay overpriced price on patreon during months and months and get full game
3 - you aint pay anything and get it free here.
4 - you buy it on steam and get patreon update here ( wich is technically legit imho as beta update arent specific release )
I need to correct you:
1) You pay full price and will eventually get full game, when it gets out of early access. All new content when released is stable with low amount of bugs.
2) You do not get full game, but test builds early. And those are really buggy, especially alphas. They are cool as early demos of new content, but that's it.
3) change to maybe... there were stable releases that were never posted here, for example
4) if you want to at least a little bit support the devs, do this one. And use alphas/betas as demos only. $15 for eventually finished product ($8 commonly on sales) is pittance to any kind of Patron subscription of any other game on this site.