Your experience was certainly true. It is why so many are trying to come here. But things have changed and the experience is not what it used to be. If you think it was difficult before, think about how it has to be now for people to choose to go back instead of persevering. The trend is clear. Things changed. The US can either fix it and remain competitive by hoarding talents. Or it will continue to deteriorate.
There are always warning signs. Immigration laws has been called antiquated and desperately in need of reform for a long time. Your sentiment of "it was good in my time" is how hegemons like Britain fell.
Countries like Monaco, Bahrain, Qatar, Hong Kong are in the >40% while Canada, Norway, Sweden are all < 20%. The US is 15%. All about the same.
https://worldpopulationreview.com/country-rankings/immigrati...
>The United States is home to the highest number of immigrants in the world. An estimated 50.6 million people in the United States—a bit more than 15% of the total population of 331.4 million—were born in a foreign country. The number of immigrants in the U.S. has increased by at least 400% since 1965.
By the way, the USA takes more immigrants every year than any other country in the world. I myself went through the process and was treated with complete respect and it wasn't easy but well worth it to become an American and be welcomed into the Land of Milk and Honey.