These are not mutually exclusive. I want a better life, and I also have career ambition and skills that I'm willing to deploy in a place that will give me a better life in return.
You want a better life, the country providing it is arbitrary as long as it accepts the currency that you can provide for that better life by your skill set.
If it was altruistic you would emigrate because you believe in the country you are emigrating to even if it meant your life was worse.
There is nothing wrong with that. I'm selfish, you're selfish, the government is selfish, everyone in the host country is selfish. It's human nature. We all want good lives. That's the reason a transactional economy exists. It's good for the country's GDP and overall economy to welcome outside talent, and that outside talent enjoys being rewarded for their contributions, and over time, their new place of residence becomes a part of their cultural identity. That's how things usually work.
Not everyone is a saint.
> If it was altruistic you would emigrate because you believe in the country you are emigrating to even if it meant your life was worse.
Reality check: 99% of people would take a better life over a worse life. And there's nothing wrong with that. The entire world is built with this as a base assumption.
Also, reality check: Life in the US kinda sucks unless you have a well-paying skilled job or a lot of money. In either case you'll be contributing to the economy.
And it seems you agree: people don’t move to a new place to contribute their skills.
They move because of the potential upsides for themselves.
My comment was about why this was not a “it’s both” type of situation. So just own your motivation for what it is—you emigrate so you can get a better life in a new country than you can get in your old country. That’s honorable enough.