I'm generating the same kind of income, though my investment costs were waaaaayyy less. I know everyone is not a fan, and some people are very sceptical, but Bitcoin mining has given me total freedom from the corporate office job I used to have.
My initial investment was around $30 000, and I now generate anything between $1500 - $3000 per month. Just letting you know, there are alternatives :)
That was a good move @andriesvw! Awesome that you have been able to do that :-)