Estimate ~10 hours average total effort to prepare each proposal (which might be low), so ~28,000 hours, or ~14 years of full time labor. Almost all of that is uncompensated work by highly skilled people. For an 8% chance to be able to start the project, most likely with below-market compensation.
@aussiastronomer.bsky.socialOof, only an ~8% selection rate for JWST proposals (225 out of 2855 proposals!).