It is foolish to place our confidence in the created and reject God (30:1-17), since God is jealous to care for His people and curse their foes (30:18-33), so that He is celebrated among us (31:1-9).
Isa 30:15-18 CSB
15 For the Lord God, the Holy One of Israel, has said:
“You will be delivered by returning and resting;
your strength will lie in quiet confidence.
But you are not willing.”
16 You say, “No!
We will escape on horses”—
therefore you will escape!—
and, “We will ride on fast horses”—
but those who pursue you will be faster.
17 One thousand will flee at the threat of one,
at the threat of five you will flee,
until you remain
like a solitary pole on a mountaintop
or a banner on a hill.
18 Therefore the Lord is waiting to show you mercy,
and is rising up to show you compassion,
for the Lord is a just God.
All who wait patiently for him are happy.