I only have 50 as well but I rarely actually receive lives but get tons of requests for lives. I'm thinking it's a ploy for players to spend more money which for me makes me just want to stop playing.
I'm having the same issue, I'm getting lots of requests but hardly receive any and that makes me have to wait a while before I can play again, especially in hard levels. It's pretty much getting to the point where you have to spend a lot of money to get through these levels.