Is refusing to marry a well-off Muslim due to not being attracted to him considered a sin, and what are the harms of that to the individual and society?

This is not considered a sin, for psychological conviction has its place in Islam, and a woman does not sin by rejecting a man due to something in his physical appearance. However, if you fear missing out on marriage, then abandon capriciousness and use your intellect. A woman may be punished if she follows her whims in rejecting a man of religion and good character, by remaining unmarried.