You are begging the question (as in a circular argument). Imagine a disease that is always fatal. You could:
A) Not vaccinate. Everyone will die.
B) Vaccinate. Two outcomes:
B.1) The virus might work; nobody will die.
B.2) The virus might escape; everyone will still die.
Like about 95% of the population I'd rather go for the B.1 route rather than the inevitability of A and hope that B.2 doesn't arise. But if B2 does arise there is still:
B2.1) Vaccines are tweaked against the escape variants as they arise and given as annual boosters like influenza vaccines. Some will die but most won't.
I can't think of a single reason why anyone would prefer option A.