Why dont people keep the sabbath on the 7th day like it says in the bible?

Some people claim that the sabbath is on Sunday, but the truth is, the sabbath begins at sunset on Friday and ends at sunset on Saturday, as it always has. However, the Ten Commandments and the sabbath are of the Old Covenant, and Christians who rely on following the Old Covenant laws are under a curse. (Galatians 3:10) The commandment to observe the sabbath is the only one of the Ten Commandments which are not reiterated in the New Testament. Christians are to meet on the first day of the week, (Acts 20:7) (Even if it were true that that scripture were talking about Saturday after sunset, it is still not on the sabbath, because the sabbath ends Saturday at sunset.