But it is also not infinitely cheaper. It involves time commitment. Large projects are thousands and thousands of man months, and you can download and build it by paying $0. People seems to be willing to spend a significant amount of time for something that is distributed for $0.
It is effectively infinitely easier. Hackers don't need multi-year studies, trials and FDA approvals before pushing code to Github. The fact that there are no "open source drugs" should give you a hint that the analogy you're trying to draw is fundamentally flawed.
Drug discovery (i.e. actual drugs; NOT just hits or lead molecules) is not as simple as pounding code on the couch in your jammies.