For a 10% drop rate the likelihood of going 0/75 would be .04%.
For an 8% drop rate the likelihood of going 0/75 would be .19%.

For a 10% likelihood of going 0/75 the drop rate would have to be ~3%.
For a 50% likelihood of going 0/75 the drop rate would have to be ~1%.

Someone who has done this BCNM 75 times has too much time on their hands about 80% of the time.

Doing that BCNM 75 times would cost 3,000 Beastmen's Seals.