Are you trying to tell me that until someone becomes a citizen in the US, they pay no taxes whatsoever? I find that hard to believe.
No, that's not what I'm saying.
This is so laughably silly I don't even know where to begin.
First of all, I was a temporary immigrant to the US and I immediately was on the hook for a bunch of money as part of my visa application process. So immediately I'd argue your first point is incorrect on that technicality anyway, not to mention I was basically moving to the US to start a business so then spent the next two years dumping money into the economy.
What is your expectation of responsibility here? You can be sick and not know you're sick. You can be sick and asymptomatic. You can be sick and think you're sick with something basic like a cold but it's actually the flu or COVID or something else more sinister.
Pretending that anyone is going to adhere to an undefined system of responsibility at the best of times, let alone when it comes to moving overseas into a different country, seems ludicrous to me - I'm supposed to cancel might flight and re-arrange my immigration plans because I have a runny nose?
If you want to have a healthy country you need publicly accessible healthcare for everyone. We literally just had an object lesson in this with the COVID pandemic - indeed, we're still in the middle of the object lesson, where people's sense of "responsibility" towards others when it comes to communicable diseases is visible everywhere you look.
And even if you were right, which you're not, you'd be wrong about 10 minutes after the average immigrant turns up when they first have to buy something and pay sales tax.
The "sense of entitlement" exists in your head. I'm noting that if you want to have a healthy society, a plan to look after sick people is a necessity. Your sort of thinking is exactly why almost one in three hundred Americans died in the first year of the pandemic.
FWIW I left the US for the UK in 2016. Before arriving there I had to pay into their national health insurance scheme. If you object to immigrants coming and not paying their way you could agitate for such a scheme. But I assume that's not the point.
Anyway, looks like you're going to get what you want and nobody is going to come to the US any more. You'll get to see what it's like when it works like that.
It is absolutely the host country's responsibility to do this to keep their own citizens safe.