Going by what I could make as an IM vs what I could make as a hospital midwife, in this country, I don't think many midwives really cash in on it. Working for the hospital, I could be making on average $61 000 but as an IM, it would be about half that due to costs. Where I live, that is not enough to be comfortable to pay off a mortgage or have any time with my husband out of work because he only earns $30 000 in the job he is in. It seems like a lot but when you take out how much it costs to actually be able to have the resources, it isn't.
IM work separate from organisations to be able to work with the freedom of their own "policies" rather than having to make decisions based on the fact they are working under someone else.
That said, I do know of one midwive who will charge $10 000 AUD to keep the whole month free for you. So she is charging you waaaay more to work less. Sounds like cashing in to me.