OP, let me google that for you:
https://www.nolo.com/legal-encyclopedia/free-books/fiance-marriage-visa-book/chapter3-5.html
The link above says, "The Form I-864 Affidavit of Support is a legally enforceable contract, meaning that either the government or the sponsored immigrant can take the sponsor to court if the sponsor fails to provide adequate support to the immigrant. In fact, the law places more obligations on the sponsor than on the immigrant—the immigrant could decide to quit a job and sue the sponsor for support."
It goes on to say, "The sponsor's responsibility lasts until the immigrant becomes a U.S. citizen, has earned 40 work quarters credited toward Social Security (a work quarter is about three months, so this means about ten years of work), dies, or permanently leaves the United States. If the immigrant has already been living in the U.S. and earned work credits before applying for the green card, those count toward the 40."
You would be COMPLETELY INSANE to agree to this.