Actually he does not say paid nor is Paul taking money at any point, that is something the church has put in there.
Luke 10 Jesus tells us exactly what it means. This is not a "theory" it is a matter of fact. Paul is quoting Jesus.
5 And into whatsoever house ye enter, first say, Peace be to this house.
6 And if the son of peace be there, your peace shall rest upon it: if not, it shall turn to you again.
7 And in the same house remain, eating and drinking such things as they give: for the labourer is worthy of his hire. Go not from house to house. ( a labourer is worth his hire/wages, he tells us what that is, eating and drinking what is given to you that day you minister) it is really that simple.
8 And into whatsoever city ye enter, and they receive you, eat such things as are set before you:
(in case it was not clear, Jesus repeats himself, eat those things they give you, as you better because that is your pay)