An idea I've come across I propose in good faith: The reason mass migration is bipartisanly supported is because the overwhelming majority of Westerners want to believe the West is the pinnacle of civilization; which is best evidenced by people wanting to migrate to it
It's far too complex a topic, but the fundamental reason is essentially the victory of French revolutionary thought across institutions in the West and attempting to remove all forms of hierarchy in existence so that mankind can finally fulfill their paradisaical state of nature.
This is why simply identifying as a thing (eg: I am British because my passport says so) and circular reasoning (a woman is a person that identifies as a woman) is so in vogue in the institutions.
Mass migration fulfills this simultaneously: all those 100% English people who just happened to be born in Uttar Pradesh can finally come to their home country, and the mass turmoil and societal alienation will give the state the reason to continue with it's repression of native consciousness and venerating the foreign. It's a Fabian tactic, similar to Lenin printing the Ruble into nothing because it would lead to a non-monetary barter system, a step closer to his revolutionary paradise.
The reason it's bipartisan is because the institutions, from cradle to grave, are 100% behind this. Lefties and righties in power go to the same schools and universities and disagree only on the margins. Those who fall outside the margins (eg: the left as embodied in Marine Le Pen and the right as embodied in Rupert Lowe, there are others too) are shunned and repressed by the institutions as much as they are able, who then hide behind impartiality when questioned (eg: Marine Le Pen getting into all sorts of issues with campaign financing despite doing exactly what she was supposed to because the rules are so contradictory, and intentionally so, but enforced only on those outside the institutional margin).
You underestimate just how much of a shithole India is and how far we'd have to fall for them to leave.
Our economy is set to implode within a decade due to structural dysfunction the nation is incapable of fixing, and since we can't force the world to accept our printed money as the petrodollar fades and national-debt holders lose faith in payment. We have two infinitely expanding bubbles in AI and housing, and a cultural demand for infinite growth.
This is like my fourth reminder in this thread on just how abjectively hellish of a shithole India is.
@Fcret is correct in terms of just how much we'd need to fall to get them to voluntarily leave.
US GDP per capita is roughly $90,000 against India's around $2,800 per capita.
For context, the US GDP per capita (in today's dollars) in 1930 following the massive collapse of 1929 was about $6,000 to $8,000, at least twice to almost three times as productive as India today. In the same period, Indian GDP per capita was around $1,000 in today's terms. That's 17% the productivity then versus 3% the productivity. The US grew by about 15 to 11.3 times in GDP per capita, versus India's paltry 2.8 times, over almost 100 years.
The West could collapse tomorrow, and so long as GDP per capita remained above where they were in the 1880s they would be on par or wealthier than India.
Even middling OECD countries like Australia or South Korea would be looking at retaining the 1970s/1980s productivity to exceed modern India. The worst performing OECD state, Colombia, last matched India's GDP per capita in 2004 and has tripled since.
So yeah, there could be a disaster that completely wipes out 75% of the economy of the OECD and there'd be only a handful of countries worse than India. The rest would still performing at levels of historical booms, or historical shrinking where families still owned a car and had a stay-at-home wife. This isn't even taking into account the fact that culturally you wouldn't be living somewhere where your societal value is measured by star signs at your birth, or where eating shit and piss is a holy activity.
India is essentially Bombay, Mumbai, Calcutta, New Delhi and Chennai propping up 1.4 billion people who don't have running water.