Ok, I agree with you to some extent.
Marriages do happen mostly because of the green card the other person has. However, not all situations are like that. Divorce rates are high everywhere, and it's not only "Indian people" who are divorcing each other.
The arranged marriage is a custom, that has been followed for many hundreds of years, but it hasn't been the same all throughout. Times have changed and so have marriages. People are now choosing their partners, and are taking action if they are unhappy with its outcome. Yes, they can still remarry after having a divorce. At least, that is what I think can happen in the urban areas. Things are different in the rural areas, where honor, pride, and respect matter above everything else.
Frankly, it should be none of our business. It's their life. They can do whatever they want with it.