No one forces you to buy it now. Other players are paying this price to play early. The regular price is $10 and it will be available at that price on Wednesday, August 7.
NEW UPDATE HAS BEEN RELEASED! How to Fix the Future: Chapter 2, Part Two(2) (v0.3.2) is now available for $30! » Comments
The full game cost 10$. You pay once. You just get new updates later if you paid the regular price. Patrons and those who purchased on itch by higher price get updates earlier. So I just increase itch prices for a few days to match my patreon tiers on new releases. That's it. Consider this as an early access.
You don't have to pay twice or by chapter. Just wait until it's available for $10.