Despite the many warnings that the Bible puts before us, as well as the obvious limitations that we have in life, not the least of which are our physical health, or our short lifespan, when compared to the centuries of history, people continue to disregard the word of God, by ignoring their obligation to learn from the instruction of a daily study, and otherwise do not take seriously the warnings that exist within the Bible.
The land of my people, refers to the Israelites, but also refers to all of Gods people, throughout the world, and throughout history.
Without a spiritual life, which is the land of milk and honey so to speak, there can only be thorns and briers.
The houses of joy, refers to the opulent homes of the wealthy.
Isaiah begins with a warning to all people in general, and then expands the warning to those who have homes of joy, indicating prosperity, and success, and wealth.
The point is that, the destruction will be widespread, and felt by everyone. No one will be left unaffected. No one will be excluded from the destruction. Whether rich or poor, fat or lean, the sin of ignoring God and His provision, will be destruction.
Realize, that all blessing comes from God. Blessing comes from no other source.
And if you reject God, then you obviously reject blessing.
And if you have no blessing, then you have thorns and briers.
And, it matters not what your status is in this world, because everyone has to deal with truth and reality, and there is no dual set of realities, one for the rich and one for the poor.
Just as the lifespan ends in death for everyone, rich or poor, happy or sad, so too, we all have to face the repercussions of our choices in life, whether they be for doctrine and our spiritual life, or without them.