For me personally, butterflies have kinda been the holy grail.
Having said that, I have never simply purchased a midpoint fly and waited for a target. I started there, like everyone else - then I went through the same path as others that have gotten deep into the strategy.
As it moves you want to further limit risk while exposing additional profitability. As max has said, consider time frames, ratios and additional spreads that limit downside and enhance the profitability chart. If this type of trading suits your personality and you spend the time to develop the techniques around the butterfly, the rewards can be quite significant.