Though there are all sorts sinful forms of self-interest, self-interest itself isn’t inherently sinful. In fact, there are a lot of good forms of self-interest the Bible approves of and even uses as motivators to live faithful lives.

Wayne Grudem explains:

Much self-interest is good and approved by Scripture, as when Jesus commands us to “lay up for yourselves treasures in heaven” (Matt. 6: 20), or when we seek to grow in sanctification and Christian maturity (1 Thess. 4: 3), or even when we come to God through Christ for salvation. God certainly appeals to the self-interest of sinful people when he says, “Turn back, turn back from your evil ways; for why will you die, O house of Israel?” (Ezek. 33: 11). To define the essential character of sin as selfishness will lead many people to think that they should abandon all desire for their own personal benefit, which is certainly contrary to Scripture. (Taken from Systematic Theology: An Introduction to Biblical Doctrine) p. 491).

Deny the kinds of self-interest that drives you to sin, but not the kind that drives you to holiness.