[moneysavingexpert.com]If you don't want to lend someone help, kindly do not announce it to the world. The person asking you for your help has a reason for doing so if you find his reasons not strong enough to justify your assistance, reply with a polite regret letter, wish them well; and move on from it.
Different things mean different things to different people. There are people who rate weddings higher than school fees; so you are not going to lecture people on the things they need to seek help for and the things they should not seek help for.
If you feel you want to manage someone's life, kindly proceed to make an application for the same without unnecessarily lecturing them, and the world, on why you think they are focusing their attention in the wrong investment path.
People derive happiness in different ways, maybe that wedding meant a lot to that couple more than the sickness you are anticipating for them that will not come. If you do not want to lend a hand on anything under the sun, be nice while at it and move on with your life without raising unnecessary dust.
You are not the Dalai Lama, so stop acting like the paragon of virtue.