Lots of trust was placed in horses and chariots during the days of ancient Israel. God warned against their trusting in these fading, physical things. The Psalmist wrote- "Some trust in chariots and some in horses, but we trust in the name of the LORD our God" (20:7).
We look to so many things for happiness, joy, and fulfillment. We see earthly items and think they'll give us security and contentment, but they never do. Raymond Ortlund addresses this very tendency in his sermon on Isaiah 31 and 32-
“The richness and fullness of life come from what is spiritual, not earthly. Money, for example, can buy a house, but it can’t make a home. Money can put food on the table, but it can’t put laughter and joy around that table. Money can fly you to Paris, but it can’t kindle romance there. What money can do is make you an attractive target for thieves and lawsuits. There is no security in money. There is no life for us in any tangible thing. What makes for life comes not from this world but from the grace of God. Therefore, a heart at one with God is the secret to life. To have God is to have all things. To trust him is to be saved.”