Ask HN: Are microloans a scam?

I believe many at HN must be Kiva users and have lent many loans. I support the cause and good will behind it but there seem to be more here

Today I happened to glance over "Portfolio Yield" of field partners. It's as high as 54% for many. Even then some of them are reporting negative profitability or maximum as little as 5%.

They are operating in third world countries and making millions from poor borrowers at exorbitant interest rates; even higher than credit cards. How's that possible and is this all operation some scam like aid to African countries?