True.

With respect to costs, when steem was 10 cents, top witnesses made 1380SP per day due to the high inflation at the time. Which was changed at a later HF.

If your server cost was $200 a month for example, you'll need to make enough blocks to cover that cost and if you need to withdraw that SP to pay for it you'll need to wait a while to be able to power down and withdraw. So it's not great for lower ranking witnesses to be running a server at lower prices.