To put some numbers to trying to develop a single therapy (where candidates etc. will fail as you try them)
- Plan to sink $180-500M+ just in R&D
- Factor in failures, regulatory, clinical, recruitment, phase 1/2 trials and you arrive very quickly around $1.3-2.1 BILLION USD per therapy approved.
...there is a 90% chance that you will spend that $1B+ - and it will fail completely.
According to your numbers, Moderna got lucky at a 10% chance of producing the mRNA COVID-19 vaccine in 48 hours of computation? I don't know, but there seems to be more factors at play.
Moderna got lucky in that we know enough about that virus that the chance of a COVID-19 vaccine was a lot more than 10%. The more general case of a drug is a lot more than specific one