I appreciate how you asked this :D.
Yeah, if someone paid for every monthly build, it would definitely add up and be much higher than the retail value of the game. The idea isn’t that people need to grab every update -- It’s supporting the development when and if you feel like it. You get the latest build (which includes all previous H content) for that month’s support. No pressure to stay subbed forever or purchase every dev release on itch. Even I haven't stayed subbed to most H games I support for the entirety of their development span.
That said, we do plan to offer a standard one-time purchase when we hit Early Access. So if the monthly model doesn’t work for you, waiting for that version might be the better fit.
Appreciate you asking in good faith!