"Whoever sins is a slave to sin". What did Jesus mean by this?

It means that the sin directs your actions.

One might say instead: you are the slave of your sinful desires, you are not completely in control of your own actions.

P.S. (Did you ever try to not engage in a particular sin, but did anyway?)

Whoever sins is a slave to sin - it's similar to saying, Whoever follows Jesus is a slave to Jesus.

It's bad to be a slave. Toss out your ancient superstitious beliefs, Christianity is a master, and Christians are the pitiful slaves.

Everybody sins and is a slave to the master sin. If Jesus sets us free, we are free indeed.

The apostle Paul illustrated the condition of Adam’s offspring by likening it to that of a first-century slave. Because of inherited sin, Adam and Eve’s children were inescapably born “slaves of sin,” destined to die. (Romans 5:12; 6:16, 17) Inescapably, that is, were it not for the legal remedy that Jehovah provided in order to purchase the freedom of such slaves. Paul explained: “As through one trespass [that of Adam] the result to men of all sorts was condemnation, likewise also through one act of justification the result to men of all sorts is a declaring of them righteous for life.” That “act of justification” led to Jesus’ sacrifice of his own perfect human life as “a corresponding ransom for all.” Jehovah recognized the ransom’s legal power to release mankind from “the judgment” of “condemnation.”—Romans 5:16, 18, 19; 1 Timothy 2:5, 6.

There's so very little evidence that we have any actual sayings of Jesus. These days it seems it absolute relativism that prevails. ie, nothing is a sin .Ergo, it means whatever you want it to mean

Sin enslaves.