Gentlemen,
I'm a permanent resident and I have green card. I was born in Russia but lived my whole life in Ukraine. My parents had Ukrainian passport but no more as they have naturalized. I was over 18 so I didn't naturalize with them. So, I don't really have any passport of any country.
Should I start applying for U.S. passport? I'm sort of scared of being deported for something, is that a valid reason for getting a passort?
If you can afford it, there is really no reason not to, even if you didn't have the additional complications with unclear other citizenships.
The only people who should be careful about applying for US citizenship are those from countries (like Japan) who are barred from having dual citizenships; otherwise if you can afford it, it is frankly a no-brainer.
Plus, if you are a citizen you can vote. I don't know about you, but living and paying taxes in a country where I don't have the right to vote kinda drives me crazy.
I am not a lawyer, but look on the bright side, my opinion was free.