i think it's mainly due to western society not having as close family bonds.
so they see family as a burden rather than an integral way of living.
put it this way you wouldn't be here if your family thought the same way in the past. who do you rely on if you have no family? who can you ask for help in times of needs? basically western people, especially men are selfish. it's my money, i'm scared to lose it, i don't want to be paying for kids, etc. it's all about you and your lifestyle rather than the bigger picture.