John Calvin gives this insight: "Man's nature, so to speak, is a perpetual factory of idols."
It is an excellent metaphor because of its truth. We are prone to worship many things rather than God.
Think you're not good at anything? Not true. You are good at producing idols, things and/or people you trust in more than God, things and/or people you rave about more than God.
Our sinful natures are a factory for idol production. They are designed, as it were, to produce idols. So we are naturally inclined. It takes little effort for our hearts to be drawn away from the one true God.
It's folly. The prophets mock it. Isaiah highlights idolatry's foolishness in describing the man who fells a tree, uses half of it for fire for warmth and cooking, and uses the other half to fashion a god for worship, prayer, and salvation (Isa 44:14-20). In other place he mocks the man who seeks help from a craftsman to keep his idol from toppling over (Isa 40:20).
Yes, it's folly. Lord, rescue me from such folly. Though I have no image, I make idols. Purify my heart and my worship.
(Quote source: John Calvin, Institutes of the Christian Religion, 1.11.8)