Zimbabwe - Regime Change anyone?

Why didn't anyone look at regime change in Zimbabwe? This nutcase of a guy who started by meaning well and leading the country to independence against the British and white rule under Ian Smith (and here) is out of control. Inflation is running at a whopping 100,000% and Zimbabwe has gone from a economic bread basket of Africa to her basket case. Hopefully the elections bring an end to this but it looks dismal for now...