The primary function of the witness is to ensure their witness server is operational and able to produce a block when it's called to do so.
Everything else is a bonus and we have a number of individuals that serve as witness that bring different skills and talents to the table.
If you're not aware nor willing to do the research into how to minimize server costs when running a STEEM witness that is fine, but fundamentally the witness payout is acceptable compensation and anyone wishing to become a witness can do so given enough ambition.
It's not expensive by any means to set up a seed node and witness server. In fact I'd go as far to say that anyone who's got a job or making income on their skillset can afford to do so.
You don't need a backup witness server until you get up into the top #50 list in my opinion anyways. So depending on what type of security you need for your servers for less than a case of beer a month you could run a witness server in theory.