It's simple. If suddenly 7 million jobs are lost, you'd have a massive decline in consumer spending and tremendous disruption of production in all kinds of industries because of the lost workers. All kinds of agricultural companies would lose 75% of their production and sales revenues. That's the impact of destroying such a large number of jobs in a relatively short time.
I have a supposition for you:
I suppose these are your opinions, speculation, and conjecture.
You have no sources to cite to back up your claims of any kind of devastation upon America's economy with the loss of "all illegals" from America.
And I presume you are not factoring in, either, the DRAIN to our society, in the billions, for their medical care, jail, extra law enforcement needs, educational burden in elementary schools, burden in higher educational settings, drug smuggling, rapes, murders, drunken driving accidents, etc.
So, if I find that my business partner has been engaging in illegal business practices and cooking the books to avoid paying taxes, but it is critical to the bottom line of my business and the financial impact of correcting the illegal activity would disrupt my business, then, in your mind, I should just continue to let my business partner continue his illegal activities?