maryz:”You only ask people to pray for you for their own good?”
I wish I could claim altruism and perfect love for others - but of course that would be a lie. I think that asking for prayers from other believers is a means for sharing our burdens and that God will grow our relationship to Him and bind us to each other in sharing those burdens.
When we pray to God, it confirms our utter dependence upon Him and helps us to understand our inability to sustain ourselves without Him. By praying to Saints, this seems (at least to me) to point us elsewhere for our sustenance...
Catholics ask the saints to pray. The saints no longer need anything for themselves (though they undoubtedly live in prayer of praise); we ask that they also make petition for us, who really do still need everything.