Yes, but except at the micro level you need capital to compete, and getting hold of capital means paying rent to those who already have it. If you are clever you can make more than you pay back in rent, perhaps so much that you are in a position to lend out a surplus and collect rents of your own. But once you join the rent-collecting set, your economic incentives change drastically and you'll start getting lots of offers for moat digging services.