What is funny is Paul was not even appealing to tithes in
1 Cor 9. He was appealing to Levitical duties that were performed in the temple.
1 Cor 9 (KJV)
13
Do ye not know that they which minister about holy things live of the things of the temple? and they which wait at the altar are partakers with the altar?
1 Cor 9 (ESV)
13
Do you not know that those who are employed in the temple service get their food from the temple, and those who serve at the altar share in the sacrificial offerings?
Leviticus 2
1 And when any will offer a meat offering unto the Lord, his offering shall be of fine flour; and he shall pour oil upon it, and put frankincense thereon:
2 And he shall bring it to Aaron's sons the priests: and he shall take thereout his handful of the flour thereof, and of the oil thereof, with all the frankincense thereof; and the priest shall burn the memorial of it upon the altar, to be an offering made by fire, of a sweet savour unto the Lord:
3
And the remnant of the meat offering shall be Aaron's and his sons': it is a thing most holy of the offerings of the Lord made by fire.
The levites were to eat whatever was left of the sacrifices offered in the temple. And Paul was saying by the Lord's command "Support those that preach the gospel"
It does not even have to be money. Yes, money is probably one of the easiest ways to support, but it does not have to be money.